| Age | Commit message (Collapse) | Author | Files | Lines |
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The folio_test_anon(folio)==false cases has been relocated to
folio_add_new_anon_rmap(). Additionally, four other callers consistently
pass anonymous folios.
stack 1:
remove_migration_pmd
-> folio_add_anon_rmap_pmd
-> __folio_add_anon_rmap
stack 2:
__split_huge_pmd_locked
-> folio_add_anon_rmap_ptes
-> __folio_add_anon_rmap
stack 3:
remove_migration_pmd
-> folio_add_anon_rmap_pmd
-> __folio_add_anon_rmap (RMAP_LEVEL_PMD)
stack 4:
try_to_merge_one_page
-> replace_page
-> folio_add_anon_rmap_pte
-> __folio_add_anon_rmap
__folio_add_anon_rmap() only needs to handle the cases
folio_test_anon(folio)==true now.
We can remove the !folio_test_anon(folio)) path within
__folio_add_anon_rmap() now.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Barry Song <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Tested-by: Shuai Yuan <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Chris Li <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Cc: Yu Zhao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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For the !folio_test_anon(folio) case, we can now invoke
folio_add_new_anon_rmap() with the rmap flags set to either EXCLUSIVE or
non-EXCLUSIVE. This action will suppress the VM_WARN_ON_FOLIO check
within __folio_add_anon_rmap() while initiating the process of bringing up
mTHP swapin.
static __always_inline void __folio_add_anon_rmap(struct folio *folio,
struct page *page, int nr_pages, struct vm_area_struct *vma,
unsigned long address, rmap_t flags, enum rmap_level level)
{
...
if (unlikely(!folio_test_anon(folio))) {
VM_WARN_ON_FOLIO(folio_test_large(folio) &&
level != RMAP_LEVEL_PMD, folio);
}
...
}
It also improves the code's readability. Currently, all new anonymous
folios calling folio_add_anon_rmap_ptes() are order-0. This ensures that
new folios cannot be partially exclusive; they are either entirely
exclusive or entirely shared.
A useful comment from Hugh's fix:
: Commit "mm: use folio_add_new_anon_rmap() if folio_test_anon(folio)==
: false" has extended folio_add_new_anon_rmap() to use on non-exclusive
: folios, already visible to others in swap cache and on LRU.
:
: That renders its non-atomic __folio_set_swapbacked() unsafe: it risks
: overwriting concurrent atomic operations on folio->flags, losing bits
: added or restoring bits cleared. Since it's only used in this risky way
: when folio_test_locked and !folio_test_anon, many such races are excluded;
: but, for example, isolations by folio_test_clear_lru() are vulnerable, and
: setting or clearing active.
:
: It could just use the atomic folio_set_swapbacked(); but this function
: does try to avoid atomics where it can, so use a branch instead: just
: avoid setting swapbacked when it is already set, that is good enough.
: (Swapbacked is normally stable once set: lazyfree can undo it, but only
: later, when found anon in a page table.)
:
: This fixes a lot of instability under compaction and swapping loads:
: assorted "Bad page"s, VM_BUG_ON_FOLIO()s, apparently even page double
: frees - though I've not worked out what races could lead to the latter.
[[email protected]: comment fixes, per David and akpm]
[[email protected]: lock the folio to avoid race]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: folio_add_new_anon_rmap() careful __folio_set_swapbacked()]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Barry Song <[email protected]>
Signed-off-by: Hugh Dickins <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Tested-by: Shuai Yuan <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Chris Li <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Cc: Yu Zhao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Patch series "mm: clarify folio_add_new_anon_rmap() and
__folio_add_anon_rmap()", v2.
This patchset is preparatory work for mTHP swapin.
folio_add_new_anon_rmap() assumes that new anon rmaps are always
exclusive. However, this assumption doesn’t hold true for cases like
do_swap_page(), where a new anon might be added to the swapcache and is
not necessarily exclusive.
The patchset extends the rmap flags to allow folio_add_new_anon_rmap() to
handle both exclusive and non-exclusive new anon folios. The
do_swap_page() function is updated to use this extended API with rmap
flags. Consequently, all new anon folios now consistently use
folio_add_new_anon_rmap(). The special case for !folio_test_anon() in
__folio_add_anon_rmap() can be safely removed.
In conclusion, new anon folios always use folio_add_new_anon_rmap(),
regardless of exclusivity. Old anon folios continue to use
__folio_add_anon_rmap() via folio_add_anon_rmap_pmd() and
folio_add_anon_rmap_ptes().
This patch (of 3):
In the case of a swap-in, a new anonymous folio is not necessarily
exclusive. This patch updates the rmap flags to allow a new anonymous
folio to be treated as either exclusive or non-exclusive. To maintain the
existing behavior, we always use EXCLUSIVE as the default setting.
[[email protected]: cleanup and constifications per David and akpm]
[[email protected]: fix missing doc for flags of folio_add_new_anon_rmap()]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: enhance doc for extend rmap flags arguments for folio_add_new_anon_rmap]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Barry Song <[email protected]>
Suggested-by: David Hildenbrand <[email protected]>
Tested-by: Shuai Yuan <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Baolin Wang <[email protected]>
Cc: Chris Li <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Ryan Roberts <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Cc: Yu Zhao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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'vmap allocation for size %lu failed: use vmalloc=<size> to increase size'
The above warning is seen in the kernel functionality for allocation of
the restricted virtual memory range till exhaustion.
This message is misleading because 'vmalloc=' is supported on arm32, x86
platforms and is not a valid kernel parameter on a number of other
platforms (in particular its not supported on arm64, alpha, loongarch,
arc, csky, hexagon, microblaze, mips, nios2, openrisc, parisc, m64k,
powerpc, riscv, sh, um, xtensa, s390, sparc). With the update, the output
gets modified to include the function parameters along with the start and
end of the virtual memory range allowed.
The warning message after fix on kernel version 6.10.0-rc1+:
vmalloc_node_range for size 33619968 failed: Address range restricted between 0xffff800082640000 - 0xffff800084650000
Backtrace with the misleading error message:
vmap allocation for size 33619968 failed: use vmalloc=<size> to increase size
insmod: vmalloc error: size 33554432, vm_struct allocation failed, mode:0xcc0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0
CPU: 46 PID: 1977 Comm: insmod Tainted: G E 6.10.0-rc1+ #79
Hardware name: INGRASYS Yushan Server iSystem TEMP-S000141176+10/Yushan Motherboard, BIOS 2.10.20230517 (SCP: xxx) yyyy/mm/dd
Call trace:
dump_backtrace+0xa0/0x128
show_stack+0x20/0x38
dump_stack_lvl+0x78/0x90
dump_stack+0x18/0x28
warn_alloc+0x12c/0x1b8
__vmalloc_node_range_noprof+0x28c/0x7e0
custom_init+0xb4/0xfff8 [test_driver]
do_one_initcall+0x60/0x290
do_init_module+0x68/0x250
load_module+0x236c/0x2428
init_module_from_file+0x8c/0xd8
__arm64_sys_finit_module+0x1b4/0x388
invoke_syscall+0x78/0x108
el0_svc_common.constprop.0+0x48/0xf0
do_el0_svc+0x24/0x38
el0_svc+0x3c/0x130
el0t_64_sync_handler+0x100/0x130
el0t_64_sync+0x190/0x198
[[email protected]: v5]
Link: https://lkml.kernel.org/r/CH2PR01MB5894B0182EA0B28DF2EFB916F5C72@CH2PR01MB5894.prod.exchangelabs.com
Link: https://lkml.kernel.org/r/MN2PR01MB59025CC02D1D29516527A693F5C62@MN2PR01MB5902.prod.exchangelabs.com
Signed-off-by: Shubhang Kaushik <[email protected]>
Reviewed-by: Christoph Lameter (Ampere) <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Guo Ren <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Cc: Xiongwei Song <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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when offlining
We currently have a hack for virtio-mem in place to handle memory
offlining with PageOffline pages for which we already adjusted the managed
page count.
Let's enlighten memory offlining code so we can get rid of that hack, and
document the situation.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Oscar Salvador <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Dexuan Cui <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eugenio Pérez <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Wei Liu <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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instead of PageReserved()
We currently initialize the memmap such that PG_reserved is set and the
refcount of the page is 1. In virtio-mem code, we have to manually clear
that PG_reserved flag to make memory offlining with partially hotplugged
memory blocks possible: has_unmovable_pages() would otherwise bail out on
such pages.
We want to avoid PG_reserved where possible and move to typed pages
instead. Further, we want to further enlighten memory offlining code
about PG_offline: offline pages in an online memory section. One example
is handling managed page count adjustments in a cleaner way during memory
offlining.
So let's initialize the pages with PG_offline instead of PG_reserved.
generic_online_page()->__free_pages_core() will now clear that flag before
handing that memory to the buddy.
Note that the page refcount is still 1 and would forbid offlining of such
memory except when special care is take during GOING_OFFLINE as currently
only implemented by virtio-mem.
With this change, we can now get non-PageReserved() pages in the XEN
balloon list. From what I can tell, that can already happen via
decrease_reservation(), so that should be fine.
HV-balloon should not really observe a change: partial online memory
blocks still cannot get surprise-offlined, because the refcount of these
PageOffline() pages is 1.
Update virtio-mem, HV-balloon and XEN-balloon code to be aware that
hotplugged pages are now PageOffline() instead of PageReserved() before
they are handed over to the buddy.
We'll leave the ZONE_DEVICE case alone for now.
Note that self-hosted vmemmap pages will no longer be marked as
reserved. This matches ordinary vmemmap pages allocated from the buddy
during memory hotplug. Now, really only vmemmap pages allocated from
memblock during early boot will be marked reserved. Existing
PageReserved() checks seem to be handling all relevant cases correctly
even after this change.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Acked-by: Oscar Salvador <[email protected]> [generic memory-hotplug bits]
Cc: Alexander Potapenko <[email protected]>
Cc: Dexuan Cui <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eugenio Pérez <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Wei Liu <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Patch series "mm/memory_hotplug: use PageOffline() instead of
PageReserved() for !ZONE_DEVICE".
This can be a considered a long-overdue follow-up to some parts of [1].
The patches are based on [2], but they are not strictly required -- just
makes it clearer why we can use adjust_managed_page_count() for memory
hotplug without going into details about highmem.
We stop initializing pages with PageReserved() in memory hotplug code --
except when dealing with ZONE_DEVICE for now. Instead, we use
PageOffline(): all pages are initialized to PageOffline() when onlining a
memory section, and only the ones actually getting exposed to the
system/page allocator will get PageOffline cleared.
This way, we enlighten memory hotplug more about PageOffline() pages and
can cleanup some hacks we have in virtio-mem code.
What about ZONE_DEVICE? PageOffline() is wrong, but we might just stop
using PageReserved() for them later by simply checking for
is_zone_device_page() at suitable places. That will be a separate patch
set / proposal.
This primarily affects virtio-mem, HV-balloon and XEN balloon. I only
briefly tested with virtio-mem, which benefits most from these cleanups.
[1] https://lore.kernel.org/all/[email protected]/
[2] https://lkml.kernel.org/r/[email protected]
This patch (of 3):
In preparation for further changes, let's teach __free_pages_core() about
the differences of memory hotplug handling.
Move the memory hotplug specific handling from generic_online_page() to
__free_pages_core(), use adjust_managed_page_count() on the memory hotplug
path, and spell out why memory freed via memblock cannot currently use
adjust_managed_page_count().
[[email protected]: add missed CONFIG_DEFERRED_STRUCT_PAGE_INIT]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fix up the memblock comment, per Oscar]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: add the parameter name also in the declaration]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Dexuan Cui <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eugenio Pérez <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Wei Liu <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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There are no more users of page_mkclean(), remove it and update the
document and comment.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Replaces three calls to compound_head() with one, which removes last
caller of page_mkclean().
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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After the last user of page_maybe_dma_pinned() is converted to
folio_maybe_dma_pinned(), remove page_maybe_dma_pinned() and update the
document and comment.
[[email protected]: fix pin_user_pages.rst underlining]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Patch series "mm: remove page_maybe_dma_pinned() and page_mkclean()".
Most page_maybe_dma_pinned() and page_mkclean() callers have been
converted to the folio equivalents, after two more convertsions,
remove them and update the comment and documention.
This patch (of 4):
Convert to use vm_normal_folio() and folio_maybe_dma_pinned() API, which
helps to remove page_maybe_dma_pinned() in the subsequent change.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Let's simply reinitialize the page->_mapcount directly. We can now get
rid of page_mapcount_reset().
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Tested-by: Sergey Senozhatsky <[email protected]> [zram/zsmalloc workloads]
Cc: Hyeonggon Yoo <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Let's get rid of the page_mapcount_reset() call and simply reinitialize
folio->_mapcount directly.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Tested-by: Sergey Senozhatsky <[email protected]> [zram/zsmalloc workloads]
Cc: Hyeonggon Yoo <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Let's stop using page_mapcount_reset() and clear PageBuddy using
__ClearPageBuddy() instead.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Tested-by: Sergey Senozhatsky <[email protected]> [zram/zsmalloc workloads]
Cc: Hyeonggon Yoo <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Let's clean it up: use a proper page type and store our data (offset into
a page) in the lower 16 bit as documented.
We won't be able to support 256 KiB base pages, which is acceptable.
Teach Kconfig to handle that cleanly using a new CONFIG_HAVE_ZSMALLOC.
Based on this, we should do a proper "struct zsdesc" conversion, as
proposed in [1].
This removes the last _mapcount/page_type offender.
[1] https://lore.kernel.org/all/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Tested-by: Sergey Senozhatsky <[email protected]> [zram/zsmalloc workloads]
Reviewed-by: Sergey Senozhatsky <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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As long as the owner sets a page type first, we can allow reuse of the
lower 16 bit: sufficient to store an offset into a 64 KiB page, which is
the maximum base page size in *common* configurations (ignoring the 256
KiB variant). Restrict it to the head page.
We'll use that for zsmalloc next, to set a proper type while still reusing
that field to store information (offset into a base page) that cannot go
elsewhere for now.
Let's reserve the lower 16 bit for that purpose and for catching mapcount
underflows, and let's reduce PAGE_TYPE_BASE to a single bit.
Note that we will still have to overflow the mapcount quite a lot until we
would actually indicate a valid page type.
Start handing out the type bits from highest to lowest, to make it clearer
how many bits for types we have left. Out of 15 bit we can use for types,
we currently use 6. If we run out of bits before we have better typing
(e.g., memdesc), we can always investigate storing a value instead [1].
[1] https://lore.kernel.org/all/[email protected]/
[[email protected]: fix PG_hugetlb typo, per David]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Tested-by: Sergey Senozhatsky <[email protected]> [zram/zsmalloc workloads]
Cc: Hyeonggon Yoo <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Patch series "mm: page_type, zsmalloc and page_mapcount_reset()", v2.
Wanting to remove the remaining abuser of _mapcount/page_type along with
page_mapcount_reset(), I stumbled over zsmalloc, which is yet to be
converted away from "struct page" [1].
Unfortunately, we cannot stop using the page_type field in zsmalloc code
completely for its own purposes. All other fields in "struct page" are
used one way or the other. Could we simply store a 2-byte offset value at
the beginning of each page? Likely, but that will require a bit more
work; and once we have memdesc we might want to move the offset in there
(struct zsalloc?) again.
... but we can limit the abuse to 16 bit, glue it to a page type that
must be set, and document it. page_has_type() will always successfully
indicate such zsmalloc pages, and such zsmalloc pages only.
We lose zsmalloc support for PAGE_SIZE > 64KB, which should be tolerable.
We could use more bits from the page type, but 16 bit sounds like a good
idea for now.
So clarify the _mapcount/page_type documentation, use a proper page_type
for zsmalloc, and remove page_mapcount_reset().
[1] https://lore.kernel.org/all/[email protected]/
This patch (of 6):
Let's make it clearer that _mapcount must no longer be used for own
purposes, and how _mapcount and page_type behaves nowadays (also in the
context of hugetlb folios, which are typed folios that will be mapped to
user space).
Move the documentation regarding "-1" over from page_mapcount_reset(),
which we will remove next. Move "page_type" before "mapcount", to make it
clearer what typed folios are.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: David Hildenbrand <[email protected]>
Tested-by: Sergey Senozhatsky <[email protected]> [zram/zsmalloc workloads]
Cc: Hyeonggon Yoo <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Rapoport (IBM) <[email protected]>
Cc: Minchan Kim <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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This continues the work on getting the selftests to build without
requiring people to first run "make headers" [1].
Now that the system call numbers are in the correct, checked-in locations
in the kernel tree (./tools/include/uapi/asm/unistd*.h), make sure that
the mm selftests include that file (indirectly).
Doing so provides guaranteed definitions at build time, so remove all of
the checks for "ifdef __NR_xxx" in the mm selftests, because they will
always be true (defined).
[1] commit e076eaca5906 ("selftests: break the dependency upon local
header files")
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: John Hubbard <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Jeff Xu <[email protected]>
Cc: Andrei Vagin <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Muhammad Usama Anjum <[email protected]>
Cc: Peter Xu <[email protected]>
Cc: Rich Felker <[email protected]>
Cc: Shuah Khan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
Fix used-uninitialized of `page'.
Fixes: dce7d10be4bb ("mm/madvise: optimize lazyfreeing with mTHP in madvise_free")
Reported-by: kernel test robot <[email protected]>
Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]
Cc: Lance Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
If the bitmap block that manages the inode allocation status is corrupted,
nilfs_ifile_create_inode() may allocate a new inode from the reserved
inode area where it should not be allocated.
Previous fix commit d325dc6eb763 ("nilfs2: fix use-after-free bug of
struct nilfs_root"), fixed the problem that reserved inodes with inode
numbers less than NILFS_USER_INO (=11) were incorrectly reallocated due to
bitmap corruption, but since the start number of non-reserved inodes is
read from the super block and may change, in which case inode allocation
may occur from the extended reserved inode area.
If that happens, access to that inode will cause an IO error, causing the
file system to degrade to an error state.
Fix this potential issue by adding a wraparound option to the common
metadata object allocation routine and by modifying
nilfs_ifile_create_inode() to disable the option so that it only allocates
inodes with inode numbers greater than or equal to the inode number read
in "nilfs->ns_first_ino", regardless of the bitmap status of reserved
inodes.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ryusuke Konishi <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
Syzbot reported that mounting and unmounting a specific pattern of
corrupted nilfs2 filesystem images causes a use-after-free of metadata
file inodes, which triggers a kernel bug in lru_add_fn().
As Jan Kara pointed out, this is because the link count of a metadata file
gets corrupted to 0, and nilfs_evict_inode(), which is called from iput(),
tries to delete that inode (ifile inode in this case).
The inconsistency occurs because directories containing the inode numbers
of these metadata files that should not be visible in the namespace are
read without checking.
Fix this issue by treating the inode numbers of these internal files as
errors in the sanity check helper when reading directory folios/pages.
Also thanks to Hillf Danton and Matthew Wilcox for their initial mm-layer
analysis.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ryusuke Konishi <[email protected]>
Reported-by: [email protected]
Closes: https://syzkaller.appspot.com/bug?extid=d79afb004be235636ee8
Reported-by: Jan Kara <[email protected]>
Closes: https://lkml.kernel.org/r/20240617075758.wewhukbrjod5fp5o@quack3
Tested-by: Ryusuke Konishi <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
Patch series "nilfs2: fix potential issues related to reserved inodes".
This series fixes one use-after-free issue reported by syzbot, caused by
nilfs2's internal inode being exposed in the namespace on a corrupted
filesystem, and a couple of flaws that cause problems if the starting
number of non-reserved inodes written in the on-disk super block is
intentionally (or corruptly) changed from its default value.
This patch (of 3):
In the current implementation of nilfs2, "nilfs->ns_first_ino", which
gives the first non-reserved inode number, is read from the superblock,
but its lower limit is not checked.
As a result, if a number that overlaps with the inode number range of
reserved inodes such as the root directory or metadata files is set in the
super block parameter, the inode number test macros (NILFS_MDT_INODE and
NILFS_VALID_INODE) will not function properly.
In addition, these test macros use left bit-shift calculations using with
the inode number as the shift count via the BIT macro, but the result of a
shift calculation that exceeds the bit width of an integer is undefined in
the C specification, so if "ns_first_ino" is set to a large value other
than the default value NILFS_USER_INO (=11), the macros may potentially
malfunction depending on the environment.
Fix these issues by checking the lower bound of "nilfs->ns_first_ino" and
by preventing bit shifts equal to or greater than the NILFS_USER_INO
constant in the inode number test macros.
Also, change the type of "ns_first_ino" from signed integer to unsigned
integer to avoid the need for type casting in comparisons such as the
lower bound check introduced this time.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ryusuke Konishi <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
The dirty throttling logic is interspersed with assumptions that dirty
limits in PAGE_SIZE units fit into 32-bit (so that various multiplications
fit into 64-bits). If limits end up being larger, we will hit overflows,
possible divisions by 0 etc. Fix these problems by never allowing so
large dirty limits as they have dubious practical value anyway. For
dirty_bytes / dirty_background_bytes interfaces we can just refuse to set
so large limits. For dirty_ratio / dirty_background_ratio it isn't so
simple as the dirty limit is computed from the amount of available memory
which can change due to memory hotplug etc. So when converting dirty
limits from ratios to numbers of pages, we just don't allow the result to
exceed UINT_MAX.
This is root-only triggerable problem which occurs when the operator
sets dirty limits to >16 TB.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jan Kara <[email protected]>
Reported-by: Zach O'Keefe <[email protected]>
Reviewed-By: Zach O'Keefe <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
Patch series "mm: Avoid possible overflows in dirty throttling".
Dirty throttling logic assumes dirty limits in page units fit into
32-bits. This patch series makes sure this is true (see patch 2/2 for
more details).
This patch (of 2):
This reverts commit 9319b647902cbd5cc884ac08a8a6d54ce111fc78.
The commit is broken in several ways. Firstly, the removed (u64) cast
from the multiplication will introduce a multiplication overflow on 32-bit
archs if wb_thresh * bg_thresh >= 1<<32 (which is actually common - the
default settings with 4GB of RAM will trigger this). Secondly, the
div64_u64() is unnecessarily expensive on 32-bit archs. We have
div64_ul() in case we want to be safe & cheap. Thirdly, if dirty
thresholds are larger than 1<<32 pages, then dirty balancing is going to
blow up in many other spectacular ways anyway so trying to fix one
possible overflow is just moot.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 9319b647902c ("mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again")
Signed-off-by: Jan Kara <[email protected]>
Reviewed-By: Zach O'Keefe <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
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When mm_update_owner_next() is racing with swapoff (try_to_unuse()) or
/proc or ptrace or page migration (get_task_mm()), it is impossible to
find an appropriate task_struct in the loop whose mm_struct is the same as
the target mm_struct.
If the above race condition is combined with the stress-ng-zombie and
stress-ng-dup tests, such a long loop can easily cause a Hard Lockup in
write_lock_irq() for tasklist_lock.
Recognize this situation in advance and exit early.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jinliang Zheng <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Mateusz Guzik <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Tycho Andersen <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
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Use the new KMEM_CACHE() macro instead of direct kmem_cache_create
to simplify the creation of SLAB caches.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hongfu Li <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
After commit 21fbd59136e0 ("ksm: add the ksm prefix to the names of the
ksm private structures"), we could directly use KMEM_CACHE().
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
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DAMON_LRU_SORT contains code for handling of online DAMON parameters
update edge cases. It is no more necessary since damon_commit_ctx() takes
care of the cases. Remove the unnecessary code.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
DAMON_LRU_SORT manually manipulates the DAMON context struct for online
parameters update. Since the struct contains not only input parameters
but also internal status and operation results, it is not that simple.
Indeed, we found and fixed a few bugs in the code. Now DAMON core layer
provides a function for the usage, namely damon_commit_ctx(). Replace the
manual manipulation logic with the function. The core layer function
could have its own bugs, but this change removes a source of bugs.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
DAMON_RECLAIM contains code for handling of online DAMON parameters update
edge cases. It is no more necessary since damon_commit_ctx() takes care
of the cases. Remove the unnecessary code.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
DAMON_RECLAIM manually manipulates the DAMON context struct for online
parameters update. Since the struct contains not only input parameters
but also internal status and operation results, it is not that simple.
Indeed, we found and fixed a few bugs in the code. Now DAMON core layer
provides a function for the usage, namely damon_commit_ctx(). Replace the
manual manipulation logic with the function. The core layer function
could have its own bugs, but this change removes a source of bugs.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
*_set_{schemes,scheme_filters,quota_score,schemes}()
The functions were for updating DAMON structs that may or may not be
partially populated. Hence it was not for only adding items, but also
removing unnecessary items and updating items in-place. A previous commit
has changed the functions to assume the structs are not partially
populated, and do only adding items. Make the names better explain the
behavior.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
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damon/sysfs-schemes.c contains code for handling of online DAMON
parameters update edge cases. The logics are no more necessary since
damon_commit_ctx() and damon_commit_quota_goals() takes care of the cases.
Remove the unnecessary code.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
The function was for updating DAMON structs that may or may not be
partially populated. Hence it was not for only adding items, but also
removing unnecessary items and updating items in-place. A previous commit
has changed the function to assume the structs are not partially
populated, and do only adding items. Make the function name better
explain the behavior.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
damon/sysfs.c contains code for handling of online DAMON parameters update
edge cases. It is no more necessary since damon_commit_ctx() takes care
of the cases. Remove the unnecessary code.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
DAMON_SYSFS manually manipulates the DAMOS quota structs for online quotal
goals parameter update. Since the struct contains not only input
parameters but also internal status and operation results, it is not that
simple. Now DAMON core layer provides a function for the usage, namely
damon_commit_quota_goals(). Replace the manual manipulation logic with
the function. The core layer function could have its own bugs, but this
change removes a source of bugs.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
DAMON_SYSFS manually manipulates DAMON context structs for online
parameters update. Since the struct contains not only input parameters
but also internal status and operation results, it is not that simple.
Indeed, we found and fixed a few bugs in the code. Now DAMON core layer
provides a function for the usage, namely damon_commit_ctx(). Replace the
manual manipulation logic with the function. The core layer function
could have its own bugs, but this change removes a source of bugs.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
Implement functions for supporting online DAMON context level parameters
update. The function receives two DAMON context structs. One is the
struct that currently being used by a kdamond and therefore to be updated.
The other one contains the parameters to be applied to the first one.
The function applies the new parameters to the destination struct while
keeping/updating the internal status and operation results. The function
should be called from DAMON context-update-safe place, like DAMON
callbacks.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
Patch series "mm/damon: introduce DAMON parameters online commit function".
DAMON context struct (damon_ctx) contains user requests (parameters),
internal status, and operation results. For flexible usages, DAMON API
users are encouraged to manually manipulate the struct. That works well
for simple use cases. However, it has turned out that it is not that
simple at least for online parameters udpate. It is easy to forget
properly maintaining internal status and operation results. Also, such
manual manipulation for online tuning is implemented multiple times on
DAMON API users including DAMON sysfs interface, DAMON_RECLAIM and
DAMON_LRU_SORT. As a result, we have multiple sources of bugs for same
problem. Actually we found and fixed a few bugs from online parameter
updating of DAMON API users.
Implement a function for online DAMON parameters update in core layer, and
replace DAMON API users' manual manipulation code for the use case. The
core layer function could still have bugs, but this change reduces the
source of bugs for the problem to one place.
This patch (of 12):
Implement functions for supporting online DAMOS quota goals parameters
update. The function receives two DAMOS quota structs. One is the struct
that currently being used by a kdamond and therefore to be updated. The
other one contains the parameters to be applied to the first one. The
function applies the new parameters to the destination struct while
keeping/updating the internal status. The function should be called from
parameters-update safe place, like DAMON callbacks.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
mem_cgroup_migrate() will clear the memcg data of the old folio,
therefore, the callers must make sure the old folio is no longer on the
LRU list, otherwise the old folio can not get the correct lruvec object
without the memcg data, which could lead to potential problems [1].
Thus adding a VM_BUG_ON_FOLIO() to catch this issue.
[1] https://lore.kernel.org/all/5ab860d8ee987955e917748f9d6da525d3b52690.1718326003.git.baolin.wang@linux.alibaba.com/
Link: https://lkml.kernel.org/r/66d181c41b7ced35dbd39ffd3f5774a11aef266a.1718327124.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <[email protected]>
Suggested-by: Shakeel Butt <[email protected]>
Acked-by: Shakeel Butt <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Roman Gushchin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
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This patch adds damon description for "migrate_hot" and "migrate_cold"
actions for both usage and design documents as long as a new
"target_nid" knob to set the migration target node.
[[email protected]: trivial fixups for DAMOS_MIGRATE_{HOT,COLD} documentation]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Honggyu Kim <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>Reviewed-by: SeongJae Park <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Hyeongtak Ji <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
This patch introduces DAMOS_MIGRATE_HOT action, which is similar to
DAMOS_MIGRATE_COLD, but proritizes hot pages.
It migrates pages inside the given region to the 'target_nid' NUMA node
in the sysfs.
Here is one of the example usage of this 'migrate_hot' action.
$ cd /sys/kernel/mm/damon/admin/kdamonds/<N>
$ cat contexts/<N>/schemes/<N>/action
migrate_hot
$ echo 0 > contexts/<N>/schemes/<N>/target_nid
$ echo commit > state
$ numactl -p 2 ./hot_cold 500M 600M &
$ numastat -c -p hot_cold
Per-node process memory usage (in MBs)
PID Node 0 Node 1 Node 2 Total
-------------- ------ ------ ------ -----
701 (hot_cold) 501 0 601 1101
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hyeongtak Ji <[email protected]>
Signed-off-by: Honggyu Kim <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
This patch introduces DAMOS_MIGRATE_COLD action, which is similar to
DAMOS_PAGEOUT, but migrate folios to the given 'target_nid' in the sysfs
instead of swapping them out.
The 'target_nid' sysfs knob informs the migration target node ID.
Here is one of the example usage of this 'migrate_cold' action.
$ cd /sys/kernel/mm/damon/admin/kdamonds/<N>
$ cat contexts/<N>/schemes/<N>/action
migrate_cold
$ echo 2 > contexts/<N>/schemes/<N>/target_nid
$ echo commit > state
$ numactl -p 0 ./hot_cold 500M 600M &
$ numastat -c -p hot_cold
Per-node process memory usage (in MBs)
PID Node 0 Node 1 Node 2 Total
-------------- ------ ------ ------ -----
701 (hot_cold) 501 0 601 1101
Since there are some common routines with pageout, many functions have
similar logics between pageout and migrate cold.
damon_pa_migrate_folio_list() is a minimized version of
shrink_folio_list().
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Honggyu Kim <[email protected]>
Signed-off-by: Hyeongtak Ji <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
The current patch series introduces DAMON based migration across NUMA
nodes so it'd be better to have a new migrate_reason in trace events.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Honggyu Kim <[email protected]>
Reviewed-by: SeongJae Park <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Hyeongtak Ji <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
This patch adds target_nid under
/sys/kernel/mm/damon/admin/kdamonds/<N>/contexts/<N>/schemes/<N>/
The 'target_nid' can be used as the destination node for DAMOS actions
such as DAMOS_MIGRATE_{HOT,COLD} in the follow up patches.
[[email protected]: document target_nid file]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hyeongtak Ji <[email protected]>
Signed-off-by: Honggyu Kim <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
The alloc_demote_folio can also be used for general migration including
both demotion and promotion so it'd be better to rename it from
alloc_demote_folio to alloc_migrate_folio.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Honggyu Kim <[email protected]>
Reviewed-by: SeongJae Park <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Hyeongtak Ji <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
|
|
Patch series "DAMON based tiered memory management for CXL memory", v6.
Introduction
============
With the advent of CXL/PCIe attached DRAM, which will be called simply as
CXL memory in this cover letter, some systems are becoming more
heterogeneous having memory systems with different latency and bandwidth
characteristics. They are usually handled as different NUMA nodes in
separate memory tiers and CXL memory is used as slow tiers because of its
protocol overhead compared to local DRAM.
In this kind of systems, we need to be careful placing memory pages on
proper NUMA nodes based on the memory access frequency. Otherwise, some
frequently accessed pages might reside on slow tiers and it makes
performance degradation unexpectedly. Moreover, the memory access
patterns can be changed at runtime.
To handle this problem, we need a way to monitor the memory access
patterns and migrate pages based on their access temperature. The
DAMON(Data Access MONitor) framework and its DAMOS(DAMON-based Operation
Schemes) can be useful features for monitoring and migrating pages. DAMOS
provides multiple actions based on DAMON monitoring results and it can be
used for proactive reclaim, which means swapping cold pages out with
DAMOS_PAGEOUT action, but it doesn't support migration actions such as
demotion and promotion between tiered memory nodes.
This series supports two new DAMOS actions; DAMOS_MIGRATE_HOT for
promotion from slow tiers and DAMOS_MIGRATE_COLD for demotion from fast
tiers. This prevents hot pages from being stuck on slow tiers, which
makes performance degradation and cold pages can be proactively demoted to
slow tiers so that the system can increase the chance to allocate more hot
pages to fast tiers.
The DAMON provides various tuning knobs but we found that the proactive
demotion for cold pages is especially useful when the system is running
out of memory on its fast tier nodes.
Our evaluation result shows that it reduces the performance slowdown
compared to the default memory policy from 11% to 3~5% when the system
runs under high memory pressure on its fast tier DRAM nodes.
DAMON configuration
===================
The specific DAMON configuration doesn't have to be in the scope of this
patch series, but some rough idea is better to be shared to explain the
evaluation result.
The DAMON provides many knobs for fine tuning but its configuration file
is generated by HMSDK[3]. It includes gen_config.py script that generates
a json file with the full config of DAMON knobs and it creates multiple
kdamonds for each NUMA node when the DAMON is enabled so that it can run
hot/cold based migration for tiered memory.
Evaluation Workload
===================
The performance evaluation is done with redis[4], which is a widely used
in-memory database and the memory access patterns are generated via
YCSB[5]. We have measured two different workloads with zipfian and latest
distributions but their configs are slightly modified to make memory usage
higher and execution time longer for better evaluation.
The idea of evaluation using these migrate_{hot,cold} actions covers
system-wide memory management rather than partitioning hot/cold pages of a
single workload. The default memory allocation policy creates pages to
the fast tier DRAM node first, then allocates newly created pages to the
slow tier CXL node when the DRAM node has insufficient free space. Once
the page allocation is done then those pages never move between NUMA
nodes. It's not true when using numa balancing, but it is not the scope
of this DAMON based tiered memory management support.
If the working set of redis can be fit fully into the DRAM node, then the
redis will access the fast DRAM only. Since the performance of DRAM only
is faster than partially accessing CXL memory in slow tiers, this
environment is not useful to evaluate this patch series.
To make pages of redis be distributed across fast DRAM node and slow CXL
node to evaluate our migrate_{hot,cold} actions, we pre-allocate some cold
memory externally using mmap and memset before launching redis-server. We
assumed that there are enough amount of cold memory in datacenters as
TMO[6] and TPP[7] papers mentioned.
The evaluation sequence is as follows.
1. Turn on DAMON with DAMOS_MIGRATE_COLD action for DRAM node and
DAMOS_MIGRATE_HOT action for CXL node. It demotes cold pages on DRAM
node and promotes hot pages on CXL node in a regular interval.
2. Allocate a huge block of cold memory by calling mmap and memset at
the fast tier DRAM node, then make the process sleep to make the fast
tier has insufficient space for redis-server.
3. Launch redis-server and load prebaked snapshot image, dump.rdb. The
redis-server consumes 52GB of anon pages and 33GB of file pages, but
due to the cold memory allocated at 2, it fails allocating the entire
memory of redis-server on the fast tier DRAM node so it partially
allocates the remaining on the slow tier CXL node. The ratio of
DRAM:CXL depends on the size of the pre-allocated cold memory.
4. Run YCSB to make zipfian or latest distribution of memory accesses to
redis-server, then measure its execution time when it's completed.
5. Repeat 4 over 50 times to measure the average execution time for each
run.
6. Increase the cold memory size then repeat goes to 2.
For each test at 4 took about a minute so repeating it 50 times almost
took about 1 hour for each test with a specific cold memory from 440GB to
500GB in 10GB increments for each evaluation. So it took about more than
10 hours for both zipfian and latest workloads to get the entire
evaluation results. Repeating the same test set multiple times doesn't
show much difference so I think it might be enough to make the result
reliable.
Evaluation Results
==================
All the result values are normalized to DRAM-only execution time because
the workload cannot be faster than DRAM-only unless the workload hits the
peak bandwidth but our redis test doesn't go beyond the bandwidth limit.
So the DRAM-only execution time is the ideal result without affected by
the gap between DRAM and CXL performance difference. The NUMA node
environment is as follows.
node0 - local DRAM, 512GB with a CPU socket (fast tier)
node1 - disabled
node2 - CXL DRAM, 96GB, no CPU attached (slow tier)
The following is the result of generating zipfian distribution to
redis-server and the numbers are averaged by 50 times of execution.
1. YCSB zipfian distribution read only workload
memory pressure with cold memory on node0 with 512GB of local DRAM.
====================+================================================+=========
| cold memory occupied by mmap and memset |
| 0G 440G 450G 460G 470G 480G 490G 500G |
====================+================================================+=========
Execution time normalized to DRAM-only values | GEOMEAN
--------------------+------------------------------------------------+---------
DRAM-only | 1.00 - - - - - - - | 1.00
CXL-only | 1.19 - - - - - - - | 1.19
default | - 1.00 1.05 1.08 1.12 1.14 1.18 1.18 | 1.11
DAMON tiered | - 1.03 1.03 1.03 1.03 1.03 1.07 *1.05 | 1.04
DAMON lazy | - 1.04 1.03 1.04 1.05 1.06 1.06 *1.06 | 1.05
====================+================================================+=========
CXL usage of redis-server in GB | AVERAGE
--------------------+------------------------------------------------+---------
DRAM-only | 0.0 - - - - - - - | 0.0
CXL-only | 51.4 - - - - - - - | 51.4
default | - 0.6 10.6 20.5 30.5 40.5 47.6 50.4 | 28.7
DAMON tiered | - 0.6 0.5 0.4 0.7 0.8 7.1 5.6 | 2.2
DAMON lazy | - 0.5 3.0 4.5 5.4 6.4 9.4 9.1 | 5.5
====================+================================================+=========
Each test result is based on the execution environment as follows.
DRAM-only: redis-server uses only local DRAM memory.
CXL-only: redis-server uses only CXL memory.
default: default memory policy(MPOL_DEFAULT).
numa balancing disabled.
DAMON tiered: DAMON enabled with DAMOS_MIGRATE_COLD for DRAM
nodes and DAMOS_MIGRATE_HOT for CXL nodes.
DAMON lazy: same as DAMON tiered, but turn on DAMON just
before making memory access request via YCSB.
The above result shows the "default" execution time goes up as the size of
cold memory is increased from 440G to 500G because the more cold memory
used, the more CXL memory is used for the target redis workload and this
makes the execution time increase.
However, "DAMON tiered" and other DAMON results show less slowdown because
the DAMOS_MIGRATE_COLD action at DRAM node proactively demotes
pre-allocated cold memory to CXL node and this free space at DRAM
increases more chance to allocate hot or warm pages of redis-server to
fast DRAM node. Moreover, DAMOS_MIGRATE_HOT action at CXL node also
promotes hot pages of redis-server to DRAM node actively.
As a result, it makes more memory of redis-server stay in DRAM node
compared to "default" memory policy and this makes the performance
improvement.
Please note that the result numbers of "DAMON tiered" and "DAMON lazy" at
500G are marked with * stars, which means their test results are replaced
with reproduced tests that didn't have OOM issue.
That was needed because sometimes the test processes get OOM when DRAM has
insufficient space. The DAMOS_MIGRATE_HOT doesn't kick reclaim but just
gives up migration when there is not enough space at DRAM side. The
problem happens when there is competition between normal allocation and
migration and the migration is done before normal allocation, then the
completely unrelated normal allocation can trigger reclaim, which incurs
OOM.
Because of this issue, I have also tested more cases with
"demotion_enabled" flag enabled to make such reclaim doesn't trigger OOM,
but just demote reclaimed pages. The following test results show more
tests with "kswapd" marked.
2. YCSB zipfian distribution read only workload (with demotion_enabled true)
memory pressure with cold memory on node0 with 512GB of local DRAM.
====================+================================================+=========
| cold memory occupied by mmap and memset |
| 0G 440G 450G 460G 470G 480G 490G 500G |
====================+================================================+=========
Execution time normalized to DRAM-only values | GEOMEAN
--------------------+------------------------------------------------+---------
DAMON tiered | - 1.03 1.03 1.03 1.03 1.03 1.07 1.05 | 1.04
DAMON lazy | - 1.04 1.03 1.04 1.05 1.06 1.06 1.06 | 1.05
DAMON tiered kswapd | - 1.03 1.03 1.03 1.03 1.02 1.02 1.03 | 1.03
DAMON lazy kswapd | - 1.04 1.04 1.04 1.03 1.05 1.04 1.05 | 1.04
====================+================================================+=========
CXL usage of redis-server in GB | AVERAGE
--------------------+------------------------------------------------+---------
DAMON tiered | - 0.6 0.5 0.4 0.7 0.8 7.1 5.6 | 2.2
DAMON lazy | - 0.5 3.0 4.5 5.4 6.4 9.4 9.1 | 5.5
DAMON tiered kswapd | - 0.0 0.0 0.4 0.5 0.1 0.8 1.0 | 0.4
DAMON lazy kswapd | - 4.2 4.6 5.3 1.7 6.8 8.1 5.8 | 5.2
====================+================================================+=========
Each test result is based on the exeuction environment as follows.
DAMON tiered: same as before
DAMON lazy: same as before
DAMON tiered kswapd: same as DAMON tiered, but turn on
/sys/kernel/mm/numa/demotion_enabled to make
kswapd or direct reclaim does demotion.
DAMON lazy kswapd: same as DAMON lazy, but turn on
/sys/kernel/mm/numa/demotion_enabled to make
kswapd or direct reclaim does demotion.
The "DAMON tiered kswapd" and "DAMON lazy kswapd" didn't trigger OOM at
all unlike other tests because kswapd and direct reclaim from DRAM node
can demote reclaimed pages to CXL node independently from DAMON actions
and their results are slightly better than without having
"demotion_enabled".
In summary, the evaluation results show that DAMON memory management with
DAMOS_MIGRATE_{HOT,COLD} actions reduces the performance slowdown compared
to the "default" memory policy from 11% to 3~5% when the system runs with
high memory pressure on its fast tier DRAM nodes.
Having these DAMOS_MIGRATE_HOT and DAMOS_MIGRATE_COLD actions can make
tiered memory systems run more efficiently under high memory pressures.
This patch (of 7):
The alloc_demote_folio can be used out of vmscan.c so it'd be better to
remove static keyword from it.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Honggyu Kim <[email protected]>
Reviewed-by: SeongJae Park <[email protected]>
Signed-off-by: SeongJae Park <[email protected]>
Cc: Gregory Price <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Hyeongtak Ji <[email protected]>
Cc: Masami Hiramatsu (Google) <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Rakie Kim <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Function deferred_[init|free]_pages are only used in
deferred_init_maxorder(), which makes sure the range to init/free is
within MAX_ORDER_NR_PAGES size.
With this knowledge, we can simplify these two functions. Since
* only the first pfn could be IS_MAX_ORDER_ALIGNED()
Also since the range passed to deferred_[init|free]_pages is always from
memblock.memory for those we have already allocated memmap to cover,
pfn_valid() always return true. Then we can remove related check.
[[email protected]: adjust function declaration indention per David]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Wei Yang <[email protected]>
Reviewed-by: Mike Rapoport (IBM) <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Dirty swap cache page could live both in page table (not page cache) and
swap cache when freshly swapped in. Correct comment.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Tony Luck <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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When user sets SIGBUS to SIG_IGN, it won't cause loop now. For action
required mce error, SIGBUS cannot be blocked. Also when a hwpoisoned page
is re-accessed, kill_accessing_process() will be called to kill the
process.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Miaohe Lin <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: kernel test robot <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Cc: Tony Luck <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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