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mm: shmem: rename mTHP shmem counters

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The legacy PMD-sized THP counters at /proc/vmstat include thp_file_alloc,
thp_file_fallback and thp_file_fallback_charge, which rather confusingly
refer to shmem THP and do not include any other types of file pages.  This
is inconsistent since in most other places in the kernel, THP counters are
explicitly separated for anon, shmem and file flavours.  However, we are
stuck with it since it constitutes a user ABI.

Recently, commit 66f44583f9 ("mm: shmem: add mTHP counters for anonymous
shmem") added equivalent mTHP stats for shmem, keeping the same "file_"
prefix in the names.  But in future, we may want to add extra stats to
cover actual file pages, at which point, it would all become very
confusing.

So let's take the opportunity to rename these new counters "shmem_" before
the change makes it upstream and the ABI becomes immutable.  While we are
at it, let's improve the documentation for the legacy counters to make it
clear that they count shmem pages only.

Link: https://lkml.kernel.org/r/20240710095503.3193901-1-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Lance Yang <ioworker0@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Ryan Roberts 2024-07-10 10:55:01 +01:00 committed by Andrew Morton
parent 2ef52d5bb7
commit 63d9866ab0
4 changed files with 29 additions and 26 deletions
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29
Documentation/admin-guide/mm/transhuge.rst
View file

@ -412,20 +412,23 @@ thp_collapse_alloc_failed
the allocation.
thp_file_alloc
is incremented every time a file huge page is successfully
allocated.
is incremented every time a shmem huge page is successfully
allocated (Note that despite being named after "file", the counter
measures only shmem).
thp_file_fallback
is incremented if a file huge page is attempted to be allocated
but fails and instead falls back to using small pages.
is incremented if a shmem huge page is attempted to be allocated
but fails and instead falls back to using small pages. (Note that
despite being named after "file", the counter measures only shmem).
thp_file_fallback_charge
is incremented if a file huge page cannot be charged and instead
is incremented if a shmem huge page cannot be charged and instead
falls back to using small pages even though the allocation was
successful.
successful. (Note that despite being named after "file", the
counter measures only shmem).
thp_file_mapped
is incremented every time a file huge page is mapped into
is incremented every time a file or shmem huge page is mapped into
user address space.
thp_split_page
@ -496,16 +499,16 @@ swpout_fallback
Usually because failed to allocate some continuous swap space
for the huge page.
file_alloc
is incremented every time a file huge page is successfully
shmem_alloc
is incremented every time a shmem huge page is successfully
allocated.
file_fallback
is incremented if a file huge page is attempted to be allocated
shmem_fallback
is incremented if a shmem huge page is attempted to be allocated
but fails and instead falls back to using small pages.
file_fallback_charge
is incremented if a file huge page cannot be charged and instead
shmem_fallback_charge
is incremented if a shmem huge page cannot be charged and instead
falls back to using small pages even though the allocation was
successful.

6
include/linux/huge_mm.h
View file

@ -269,9 +269,9 @@ enum mthp_stat_item {
MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE,
MTHP_STAT_SWPOUT,
MTHP_STAT_SWPOUT_FALLBACK,
MTHP_STAT_FILE_ALLOC,
MTHP_STAT_FILE_FALLBACK,
MTHP_STAT_FILE_FALLBACK_CHARGE,
MTHP_STAT_SHMEM_ALLOC,
MTHP_STAT_SHMEM_FALLBACK,
MTHP_STAT_SHMEM_FALLBACK_CHARGE,
MTHP_STAT_SPLIT,
MTHP_STAT_SPLIT_FAILED,
MTHP_STAT_SPLIT_DEFERRED,

12
mm/huge_memory.c
View file

@ -568,9 +568,9 @@ DEFINE_MTHP_STAT_ATTR(anon_fault_fallback, MTHP_STAT_ANON_FAULT_FALLBACK);
DEFINE_MTHP_STAT_ATTR(anon_fault_fallback_charge, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(swpout, MTHP_STAT_SWPOUT);
DEFINE_MTHP_STAT_ATTR(swpout_fallback, MTHP_STAT_SWPOUT_FALLBACK);
DEFINE_MTHP_STAT_ATTR(file_alloc, MTHP_STAT_FILE_ALLOC);
DEFINE_MTHP_STAT_ATTR(file_fallback, MTHP_STAT_FILE_FALLBACK);
DEFINE_MTHP_STAT_ATTR(file_fallback_charge, MTHP_STAT_FILE_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(shmem_alloc, MTHP_STAT_SHMEM_ALLOC);
DEFINE_MTHP_STAT_ATTR(shmem_fallback, MTHP_STAT_SHMEM_FALLBACK);
DEFINE_MTHP_STAT_ATTR(shmem_fallback_charge, MTHP_STAT_SHMEM_FALLBACK_CHARGE);
DEFINE_MTHP_STAT_ATTR(split, MTHP_STAT_SPLIT);
DEFINE_MTHP_STAT_ATTR(split_failed, MTHP_STAT_SPLIT_FAILED);
DEFINE_MTHP_STAT_ATTR(split_deferred, MTHP_STAT_SPLIT_DEFERRED);
@ -581,9 +581,9 @@ static struct attribute *stats_attrs[] = {
&anon_fault_fallback_charge_attr.attr,
&swpout_attr.attr,
&swpout_fallback_attr.attr,
&file_alloc_attr.attr,
&file_fallback_attr.attr,
&file_fallback_charge_attr.attr,
&shmem_alloc_attr.attr,
&shmem_fallback_attr.attr,
&shmem_fallback_charge_attr.attr,
&split_attr.attr,
&split_failed_attr.attr,
&split_deferred_attr.attr,

8
mm/shmem.c
View file

@ -1777,7 +1777,7 @@ static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
if (pages == HPAGE_PMD_NR)
count_vm_event(THP_FILE_FALLBACK);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
count_mthp_stat(order, MTHP_STAT_FILE_FALLBACK);
count_mthp_stat(order, MTHP_STAT_SHMEM_FALLBACK);
#endif
order = next_order(&suitable_orders, order);
}
@ -1804,8 +1804,8 @@ allocated:
count_vm_event(THP_FILE_FALLBACK_CHARGE);
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_FALLBACK);
count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_FALLBACK_CHARGE);
count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK);
count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_FALLBACK_CHARGE);
#endif
}
goto unlock;
@ -2181,7 +2181,7 @@ repeat:
if (folio_test_pmd_mappable(folio))
count_vm_event(THP_FILE_ALLOC);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
count_mthp_stat(folio_order(folio), MTHP_STAT_FILE_ALLOC);
count_mthp_stat(folio_order(folio), MTHP_STAT_SHMEM_ALLOC);
#endif
goto alloced;
}