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2021-06-29mm/debug_vm_pgtable: ensure THP availability via has_transparent_hugepage()Anshuman Khandual1-12/+51
On certain platforms, THP support could not just be validated via the build option CONFIG_TRANSPARENT_HUGEPAGE. Instead has_transparent_hugepage() also needs to be called upon to verify THP runtime support. Otherwise the debug test will just run into unusable THP helpers like in the case of a 4K hash config on powerpc platform [1]. This just moves all pfn_pmd() and pfn_pud() after THP runtime validation with has_transparent_hugepage() which prevents the mentioned problem. [1] https://bugzilla.kernel.org/show_bug.cgi?id=213069 Link: https://lkml.kernel.org/r/[email protected] Fixes: 787d563b8642 ("mm/debug_vm_pgtable: fix kernel crash by checking for THP support") Signed-off-by: Anshuman Khandual <[email protected]> Cc: Aneesh Kumar K.V <[email protected]> Cc: Christophe Leroy <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29tools/vm/page_owner_sort.c: check malloc() returnTang Bin1-0/+4
Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Zhang Shengju <[email protected]> Signed-off-by: Tang Bin <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29dax: fix ENOMEM handling in grab_mapping_entry()Jan Kara1-1/+2
grab_mapping_entry() has a bug in handling of ENOMEM condition. Suppose we have a PMD entry at index i which we are downgrading to a PTE entry. grab_mapping_entry() will set pmd_downgrade to true, lock the entry, clear the entry in xarray, and decrement mapping->nrpages. The it will call: entry = dax_make_entry(pfn_to_pfn_t(0), flags); dax_lock_entry(xas, entry); which inserts new PTE entry into xarray. However this may fail allocating the new node. We handle this by: if (xas_nomem(xas, mapping_gfp_mask(mapping) & ~__GFP_HIGHMEM)) goto retry; however pmd_downgrade stays set to true even though 'entry' returned from get_unlocked_entry() will be NULL now. And we will go again through the downgrade branch. This is mostly harmless except that mapping->nrpages is decremented again and we temporarily have an invalid entry stored in xarray. Fix the problem by setting pmd_downgrade to false each time we lookup the entry we work with so that it matches the entry we found. Link: https://lkml.kernel.org/r/[email protected] Fixes: b15cd800682f ("dax: Convert page fault handlers to XArray") Signed-off-by: Jan Kara <[email protected]> Reviewed-by: Dan Williams <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: "Aneesh Kumar K.V" <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm/kmemleak: fix possible wrong memory scanning periodYanfei Xu1-6/+12
This commit contains 3 modifications: 1. Convert the type of jiffies_scan_wait to "unsigned long". 2. Use READ/WRITE_ONCE() for accessing "jiffies_scan_wait". 3. Fix the possible wrong memory scanning period. If you set a large memory scanning period like blow, then the "secs" variable will be non-zero, however the value of "jiffies_scan_wait" will be zero. echo "scan=0x10000000" > /sys/kernel/debug/kmemleak It is because the type of the msecs_to_jiffies()'s parameter is "unsigned int", and the "secs * 1000" is larger than its max value. This in turn leads a unexpected jiffies_scan_wait, maybe zero. We corret it by replacing kstrtoul() with kstrtouint(), and check the msecs to prevent it larger than UINT_MAX. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Yanfei Xu <[email protected]> Acked-by: Catalin Marinas <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm/slub: add taint after the errors are printedGeorgi Djakov1-2/+3
When running the kernel with panic_on_taint, the usual slub debug error messages are not being printed when object corruption happens. That's because we panic in add_taint(), which is called before printing the additional information. This is a bit unfortunate as the error messages are actually very useful, especially before a panic. Let's fix this by moving add_taint() after the errors are printed on the console. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Georgi Djakov <[email protected]> Acked-by: Rafael Aquini <[email protected]> Acked-by: David Rientjes <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Reviewed-by: Aaron Tomlin <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Joonsoo Kim <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm: slub: move sysfs slab alloc/free interfaces to debugfsFaiyaz Mohammed3-93/+189
alloc_calls and free_calls implementation in sysfs have two issues, one is PAGE_SIZE limitation of sysfs and other is it does not adhere to "one value per file" rule. To overcome this issues, move the alloc_calls and free_calls implementation to debugfs. Debugfs cache will be created if SLAB_STORE_USER flag is set. Rename the alloc_calls/free_calls to alloc_traces/free_traces, to be inline with what it does. [[email protected]: fix the leak of alloc/free traces debugfs interface] Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Faiyaz Mohammed <[email protected]> Reviewed-by: Vlastimil Babka <[email protected]> Reviewed-by: Greg Kroah-Hartman <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joonsoo Kim <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29slub: force on no_hash_pointers when slub_debug is enabledStephen Boyd3-2/+22
Obscuring the pointers that slub shows when debugging makes for some confusing slub debug messages: Padding overwritten. 0x0000000079f0674a-0x000000000d4dce17 Those addresses are hashed for kernel security reasons. If we're trying to be secure with slub_debug on the commandline we have some big problems given that we dump whole chunks of kernel memory to the kernel logs. Let's force on the no_hash_pointers commandline flag when slub_debug is on the commandline. This makes slub debug messages more meaningful and if by chance a kernel address is in some slub debug object dump we will have a better chance of figuring out what went wrong. Note that we don't use %px in the slub code because we want to reduce the number of places that %px is used in the kernel. This also nicely prints a big fat warning at kernel boot if slub_debug is on the commandline so that we know that this kernel shouldn't be used on production systems. [[email protected]: fix build with CONFIG_SLUB_DEBUG=n] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Stephen Boyd <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Acked-by: Petr Mladek <[email protected]> Cc: Joe Perches <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Muchun Song <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29slub: indicate slab_fix() uses printf formatsJoe Perches1-3/+4
Ideally, slab_fix() would be marked with __printf and the format here would not use \n as that's emitted by the slab_fix(). Make these changes. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Joe Perches <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Signed-off-by: Stephen Boyd <[email protected]> Acked-by: David Rientjes <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Muchun Song <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Petr Mladek <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29slub: actually use 'message' in restore_bytes()Stephen Boyd1-1/+1
The message argument isn't used here. Let's pass the string to the printk message so that the developer can figure out what's happening, instead of guessing that a redzone is being restored, etc. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Stephen Boyd <[email protected]> Reviewed-by: Vlastimil Babka <[email protected]> Acked-by: David Rientjes <[email protected]> Reviewed-by: Muchun Song <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Joe Perches <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Petr Mladek <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29slub: restore slub_debug=- behaviorStephen Boyd1-0/+2
Petch series "slub: Print non-hashed pointers in slub debugging", v3. I was doing some debugging recently and noticed that my pointers were being hashed while slub_debug was on the kernel commandline. Let's force on the no hash pointer option when slub_debug is on the kernel commandline so that the prints are more meaningful. The first two patches are something else I noticed while looking at the code. The message argument is never used so the debugging messages are not as clear as they could be and the slub_debug=- behavior seems to be busted. Then there's a printf fixup from Joe and the final patch is the one that force disables pointer hashing. This patch (of 4): Passing slub_debug=- on the kernel commandline is supposed to disable slub debugging. This is especially useful with CONFIG_SLUB_DEBUG_ON where the default is to have slub debugging enabled in the build. Due to some code reorganization this behavior was dropped, but the code to make it work mostly stuck around. Restore the previous behavior by disabling the static key when we parse the commandline and see that we're trying to disable slub debugging. Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Fixes: ca0cab65ea2b ("mm, slub: introduce static key for slub_debug()") Signed-off-by: Stephen Boyd <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Reviewed-by: Muchun Song <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joe Perches <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Petr Mladek <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm, slub: change run-time assertion in kmalloc_index() to compile-timeHyeonggon Yoo3-9/+20
Currently when size is not supported by kmalloc_index, compiler will generate a run-time BUG() while compile-time error is also possible, and better. So change BUG to BUILD_BUG_ON_MSG to make compile-time check possible. Also remove code that allocates more than 32MB because current implementation supports only up to 32MB. [[email protected]: fix support for clang 10] Link: https://lkml.kernel.org/r/20210518181247.GA10062@hyeyoo [[email protected]: fix false-positive assert in kernel/bpf/local_storage.c] Link: https://lkml.kernel.org/r/[email protected]: https://lkml.kernel.org/r/20210511173448.GA54466@hyeyoo [[email protected]: kfence fix] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Hyeonggon Yoo <[email protected]> Signed-off-by: Vlastimil Babka <[email protected]> Reviewed-by: Vlastimil Babka <[email protected]> Signed-off-by: Marco Elver <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Marco Elver <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29slub: remove resiliency_test() functionOliver Glitta1-64/+0
Function resiliency_test() is hidden behind #ifdef SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody runs it. This function is replaced with KUnit test for SLUB added by the previous patch "selftests: add a KUnit test for SLUB debugging functionality". Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Oliver Glitta <[email protected]> Reviewed-by: Marco Elver <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Acked-by: David Rientjes <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Oliver Glitta <[email protected]> Cc: Brendan Higgins <[email protected]> Cc: Daniel Latypov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm/slub, kunit: add a KUnit test for SLUB debugging functionalityOliver Glitta6-3/+212
SLUB has resiliency_test() function which is hidden behind #ifdef SLUB_RESILIENCY_TEST that is not part of Kconfig, so nobody runs it. KUnit should be a proper replacement for it. Try changing byte in redzone after allocation and changing pointer to next free node, first byte, 50th byte and redzone byte. Check if validation finds errors. There are several differences from the original resiliency test: Tests create own caches with known state instead of corrupting shared kmalloc caches. The corruption of freepointer uses correct offset, the original resiliency test got broken with freepointer changes. Scratch changing random byte test, because it does not have meaning in this form where we need deterministic results. Add new option CONFIG_SLUB_KUNIT_TEST in Kconfig. Tests next_pointer, first_word and clobber_50th_byte do not run with KASAN option on. Because the test deliberately modifies non-allocated objects. Use kunit_resource to count errors in cache and silence bug reports. Count error whenever slab_bug() or slab_fix() is called or when the count of pages is wrong. [[email protected]: remove unused function test_exit(), from SLUB KUnit test] Link: https://lkml.kernel.org/r/[email protected] [[email protected]: export kasan_enable/disable_current to modules] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Oliver Glitta <[email protected]> Reviewed-by: Vlastimil Babka <[email protected]> Acked-by: Daniel Latypov <[email protected]> Acked-by: Marco Elver <[email protected]> Cc: Brendan Higgins <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Pekka Enberg <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29kunit: make test->lock irq safeVlastimil Babka2-9/+14
The upcoming SLUB kunit test will be calling kunit_find_named_resource() from a context with disabled interrupts. That means kunit's test->lock needs to be IRQ safe to avoid potential deadlocks and lockdep splats. This patch therefore changes the test->lock usage to spin_lock_irqsave() and spin_unlock_irqrestore(). Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Vlastimil Babka <[email protected]> Signed-off-by: Oliver Glitta <[email protected]> Reviewed-by: Brendan Higgins <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Daniel Latypov <[email protected]> Cc: David Rientjes <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Marco Elver <[email protected]> Cc: Pekka Enberg <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29slab: use __func__ to trace function namegumingtao1-6/+6
It is better to use __func__ to trace function name. Link: https://lkml.kernel.org/r/31fdbad5c45cd1e26be9ff37be321b8586b80fee.1624355507.git.gumingtao@xiaomi.com Signed-off-by: gumingtao <[email protected]> Acked-by: Christoph Lameter <[email protected]> Acked-by: David Rientjes <[email protected]> Reviewed-by: Aaron Tomlin <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Joonsoo Kim <[email protected]> Cc: Vlastimil Babka <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29doc: watchdog: modify the doc related to "watchdog/%u"Wang Qing1-5/+5
"watchdog/%u" threads has be replaced by cpu_stop_work. The current description is extremely misleading. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Wang Qing <[email protected]> Reviewed-by: Petr Mladek <[email protected]> Cc: "Guilherme G. Piccoli" <[email protected]> Cc: Joe Perches <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Kees Cook <[email protected]> Cc: Mauro Carvalho Chehab <[email protected]> Cc: Qais Yousef <[email protected]> Cc: Randy Dunlap <[email protected]> Cc: Santosh Sivaraj <[email protected]> Cc: Stephen Kitt <[email protected]> Cc: Vlastimil Babka <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29doc: watchdog: modify the explanation related to watchdog threadWang Qing1-2/+2
"watchdog/%u" threads has be replaced by cpu_stop_work. The current description is extremely misleading. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Wang Qing <[email protected]> Reviewed-by: Petr Mladek <[email protected]> Cc: "Guilherme G. Piccoli" <[email protected]> Cc: Joe Perches <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Kees Cook <[email protected]> Cc: Mauro Carvalho Chehab <[email protected]> Cc: Qais Yousef <[email protected]> Cc: Randy Dunlap <[email protected]> Cc: Santosh Sivaraj <[email protected]> Cc: Stephen Kitt <[email protected]> Cc: Vlastimil Babka <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29kernel: watchdog: modify the explanation related to watchdog threadWang Qing1-8/+4
The watchdog thread has been replaced by cpu_stop_work, modify the explanation related. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Wang Qing <[email protected]> Reviewed-by: Petr Mladek <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Mauro Carvalho Chehab <[email protected]> Cc: Joe Perches <[email protected]> Cc: Stephen Kitt <[email protected]> Cc: Kees Cook <[email protected]> Cc: Randy Dunlap <[email protected]> Cc: "Guilherme G. Piccoli" <[email protected]> Cc: Qais Yousef <[email protected]> Cc: Santosh Sivaraj <[email protected]> Cc: Vlastimil Babka <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ocfs2: remove redundant initialization of variable retColin Ian King1-1/+1
The variable ret is being initialized with a value that is never read, the assignment is redundant and can be removed. Addresses-Coverity: ("Unused value") Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Colin Ian King <[email protected]> Acked-by: Joseph Qi <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Junxiao Bi <[email protected]> Cc: Changwei Ge <[email protected]> Cc: Gang He <[email protected]> Cc: Jun Piao <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ocfs2: replace simple_strtoull() with kstrtoull()Chen Huang1-2/+3
simple_strtoull() is deprecated in some situation since it does not check for the range overflow, use kstrtoull() instead. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Chen Huang <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Junxiao Bi <[email protected]> Cc: Joseph Qi <[email protected]> Cc: Changwei Ge <[email protected]> Cc: Gang He <[email protected]> Cc: Jun Piao <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ocfs2: remove repeated uptodate check for bufferWan Jiabing1-2/+1
In commit 60f91826ca62 ("buffer: Avoid setting buffer bits that are already set"), function set_buffer_##name was added a test_bit() to check buffer, which is the same as function buffer_##name. The !buffer_uptodate(bh) here is a repeated check. Remove it. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Wan Jiabing <[email protected]> Reviewed-by: Joseph Qi <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Junxiao Bi <[email protected]> Cc: Changwei Ge <[email protected]> Cc: Gang He <[email protected]> Cc: Jun Piao <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ocfs2: remove redundant assignment to pointer queueColin Ian King1-1/+1
The pointer queue is being initialized with a value that is never read and it is being updated later with a new value. The initialization is redundant and can be removed. Addresses-Coverity: ("Unused value") Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Colin Ian King <[email protected]> Acked-by: Joseph Qi <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Junxiao Bi <[email protected]> Cc: Changwei Ge <[email protected]> Cc: Gang He <[email protected]> Cc: Jun Piao <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ocfs2: fix snprintf() checkingDan Carpenter2-11/+3
The snprintf() function returns the number of bytes which would have been printed if the buffer was large enough. In other words it can return ">= remain" but this code assumes it returns "== remain". The run time impact of this bug is not very severe. The next iteration through the loop would trigger a WARN() when we pass a negative limit to snprintf(). We would then return success instead of -E2BIG. The kernel implementation of snprintf() will never return negatives so there is no need to check and I have deleted that dead code. Link: https://lkml.kernel.org/r/20210511135350.GV1955@kadam Fixes: a860f6eb4c6a ("ocfs2: sysfile interfaces for online file check") Fixes: 74ae4e104dfc ("ocfs2: Create stack glue sysfs files.") Signed-off-by: Dan Carpenter <[email protected]> Reviewed-by: Joseph Qi <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Junxiao Bi <[email protected]> Cc: Changwei Ge <[email protected]> Cc: Gang He <[email protected]> Cc: Jun Piao <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ocfs2: remove unnecessary INIT_LIST_HEAD()Yang Yingliang1-2/+0
The list_head o2hb_node_events is initialized statically. It is unnecessary to initialize by INIT_LIST_HEAD(). Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Yang Yingliang <[email protected]> Reported-by: Hulk Robot <[email protected]> Cc: Mark Fasheh <[email protected]> Cc: Joel Becker <[email protected]> Cc: Junxiao Bi <[email protected]> Cc: Joseph Qi <[email protected]> Cc: Changwei Ge <[email protected]> Cc: Gang He <[email protected]> Cc: Jun Piao <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29squashfs: add option to panic on errorsVincent Whitchurch3-1/+91
Add an errors=panic mount option to make squashfs trigger a panic when errors are encountered, similar to several other filesystems. This allows a kernel dump to be saved using which the corruption can be analysed and debugged. Inspired by a pre-fs_context patch by Anton Eliasson. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Vincent Whitchurch <[email protected]> Signed-off-by: Phillip Lougher <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ntfs: fix validity check for file name attributeDesmond Cheong Zhi Xi1-1/+1
When checking the file name attribute, we want to ensure that it fits within the bounds of ATTR_RECORD. To do this, we should check that (attr record + file name offset + file name length) < (attr record + attr record length). However, the original check did not include the file name offset in the calculation. This means that corrupted on-disk metadata might not caught by the incorrect file name check, and lead to an invalid memory access. An example can be seen in the crash report of a memory corruption error found by Syzbot: https://syzkaller.appspot.com/bug?id=a1a1e379b225812688566745c3e2f7242bffc246 Adding the file name offset to the validity check fixes this error and passes the Syzbot reproducer test. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Desmond Cheong Zhi Xi <[email protected]> Reported-by: [email protected] Tested-by: [email protected] Acked-by: Anton Altaparmakov <[email protected]> Cc: Shuah Khan <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29scripts/spelling.txt: add more spellings to spelling.txtColin Ian King1-0/+16
Here are some of the more common spelling mistakes and typos that I've found while fixing up spelling mistakes in the kernel in the past few months. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Colin Ian King <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29streamline_config.pl: add softtabstop=4 for vim usersSteven Rostedt (VMware)1-0/+2
The tab stop for Perl files is by default (at least in emacs) to be 4 spaces, where a tab is used for all 8 spaces. Add a local variable comment to make vim do the same by default, and this will help keep the file consistent in the future when others edit it via vim and not emacs. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Steven Rostedt (VMware) <[email protected]> Cc: Masahiro Yamada <[email protected]> Cc: "John (Warthog9) Hawley" <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29streamline_config.pl: make spacing consistentSteven Rostedt (VMware)1-39/+39
Patch series "streamline_config.pl: Fix Perl spacing". Talking with John Hawley about how vim and emacs deal with Perl files with respect to tabs and spaces, I found that some of my Perl code in the kernel had inconsistent spacing. The way emacs handles Perl by default is to use 4 spaces per indent, but make all 8 spaces into a single tab. Vim does not do this by default. But if you add the vim variable control: # vim: softtabstop=4 to a perl file, it makes vim behave the same way as emacs. The first patch is to change all 8 spaces into a single tab (mostly from people editing the file with vim). The next patch adds the softtabstop variable to make vim act like emacs by default. This patch (of 2): As Perl code tends to have 4 space indentation, but uses tabs for every 8 spaces, make that consistent in the streamline_config.pl code. Replace all 8 spaces with a single tab. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Steven Rostedt (VMware) <[email protected]> Cc: "John (Warthog9) Hawley" <[email protected]> Cc: Masahiro Yamada <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ia64: mca_drv: fix incorrect array size calculationArnd Bergmann1-1/+1
gcc points out a mistake in the mca driver that goes back to before the git history: arch/ia64/kernel/mca_drv.c: In function 'init_record_index_pools': arch/ia64/kernel/mca_drv.c:346:54: error: expression does not compute the number of elements in this array; element typ e is 'int', not 'size_t' {aka 'long unsigned int'} [-Werror=sizeof-array-div] 346 | for (i = 1; i < sizeof sal_log_sect_min_sizes/sizeof(size_t); i++) | ^ This is the same as sizeof(size_t), which is two shorter than the actual array. Use the ARRAY_SIZE() macro to get the correct calculation instead. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Arnd Bergmann <[email protected]> Cc: Masahiro Yamada <[email protected]> Cc: Randy Dunlap <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29ia64: headers: drop duplicated wordsRandy Dunlap3-3/+3
Delete the repeated words "to" and "the". Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Randy Dunlap <[email protected]> Cc: Fenghua Yu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29kthread_worker: fix return value when kthread_mod_delayed_work() races with ↵Petr Mladek1-7/+12
kthread_cancel_delayed_work_sync() kthread_mod_delayed_work() might race with kthread_cancel_delayed_work_sync() or another kthread_mod_delayed_work() call. The function lets the other operation win when it sees work->canceling counter set. And it returns @false. But it should return @true as it is done by the related workqueue API, see mod_delayed_work_on(). The reason is that the return value might be used for reference counting. It has to distinguish the case when the number of queued works has changed or stayed the same. The change is safe. kthread_mod_delayed_work() return value is not checked anywhere at the moment. Link: https://lore.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Petr Mladek <[email protected]> Reported-by: Oleg Nesterov <[email protected]> Cc: Nathan Chancellor <[email protected]> Cc: Nick Desaulniers <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Minchan Kim <[email protected]> Cc: <[email protected]> Cc: Martin Liu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29kthread: switch to new kerneldoc syntax for named variable macro argumentJonathan Neuschäfer1-1/+1
The syntax without dots is available since commit 43756e347f21 ("scripts/kernel-doc: Add support for named variable macro arguments"). The same HTML output is produced with and without this patch. Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Jonathan Neuschäfer <[email protected]> Cc: Jens Axboe <[email protected]> Cc: Felix Kuehling <[email protected]> Cc: Valentin Schneider <[email protected]> Cc: Peter Zijlstra <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm/page_alloc: correct return value of populated elements if bulk array is ↵Mel Gorman1-1/+1
populated Dave Jones reported the following This made it into 5.13 final, and completely breaks NFSD for me (Serving tcp v3 mounts). Existing mounts on clients hang, as do new mounts from new clients. Rebooting the server back to rc7 everything recovers. The commit b3b64ebd3822 ("mm/page_alloc: do bulk array bounds check after checking populated elements") returns the wrong value if the array is already populated which is interpreted as an allocation failure. Dave reported this fixes his problem and it also passed a test running dbench over NFS. Link: https://lkml.kernel.org/r/[email protected] Fixes: b3b64ebd3822 ("mm/page_alloc: do bulk array bounds check after checking populated elements") Signed-off-by: Mel Gorman <[email protected]> Reported-by: Dave Jones <[email protected]> Tested-by: Dave Jones <[email protected]> Cc: Dan Carpenter <[email protected]> Cc: Jesper Dangaard Brouer <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: <[email protected]> [5.13+] Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm/page_alloc: fix memory map initialization for descending nodesMike Rapoport2-37/+58
On systems with memory nodes sorted in descending order, for instance Dell Precision WorkStation T5500, the struct pages for higher PFNs and respectively lower nodes, could be overwritten by the initialization of struct pages corresponding to the holes in the memory sections. For example for the below memory layout [ 0.245624] Early memory node ranges [ 0.248496] node 1: [mem 0x0000000000001000-0x0000000000090fff] [ 0.251376] node 1: [mem 0x0000000000100000-0x00000000dbdf8fff] [ 0.254256] node 1: [mem 0x0000000100000000-0x0000001423ffffff] [ 0.257144] node 0: [mem 0x0000001424000000-0x0000002023ffffff] the range 0x1424000000 - 0x1428000000 in the beginning of node 0 starts in the middle of a section and will be considered as a hole during the initialization of the last section in node 1. The wrong initialization of the memory map causes panic on boot when CONFIG_DEBUG_VM is enabled. Reorder loop order of the memory map initialization so that the outer loop will always iterate over populated memory regions in the ascending order and the inner loop will select the zone corresponding to the PFN range. This way initialization of the struct pages for the memory holes will be always done for the ranges that are actually not populated. [[email protected]: coding style fixes] Link: https://lkml.kernel.org/r/[email protected] Link: https://bugzilla.kernel.org/show_bug.cgi?id=213073 Link: https://lkml.kernel.org/r/[email protected] Fixes: 0740a50b9baa ("mm/page_alloc.c: refactor initialization of struct page for holes in memory layout") Signed-off-by: Mike Rapoport <[email protected]> Cc: Boris Petkov <[email protected]> Cc: Robert Shteynfeld <[email protected]> Cc: Baoquan He <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: David Hildenbrand <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-29mm/gup: fix try_grab_compound_head() race with split_huge_page()Jann Horn1-15/+43
try_grab_compound_head() is used to grab a reference to a page from get_user_pages_fast(), which is only protected against concurrent freeing of page tables (via local_irq_save()), but not against concurrent TLB flushes, freeing of data pages, or splitting of compound pages. Because no reference is held to the page when try_grab_compound_head() is called, the page may have been freed and reallocated by the time its refcount has been elevated; therefore, once we're holding a stable reference to the page, the caller re-checks whether the PTE still points to the same page (with the same access rights). The problem is that try_grab_compound_head() has to grab a reference on the head page; but between the time we look up what the head page is and the time we actually grab a reference on the head page, the compound page may have been split up (either explicitly through split_huge_page() or by freeing the compound page to the buddy allocator and then allocating its individual order-0 pages). If that happens, get_user_pages_fast() may end up returning the right page but lifting the refcount on a now-unrelated page, leading to use-after-free of pages. To fix it: Re-check whether the pages still belong together after lifting the refcount on the head page. Move anything else that checks compound_head(page) below the refcount increment. This can't actually happen on bare-metal x86 (because there, disabling IRQs locks out remote TLB flushes), but it can happen on virtualized x86 (e.g. under KVM) and probably also on arm64. The race window is pretty narrow, and constantly allocating and shattering hugepages isn't exactly fast; for now I've only managed to reproduce this in an x86 KVM guest with an artificially widened timing window (by adding a loop that repeatedly calls `inl(0x3f8 + 5)` in `try_get_compound_head()` to force VM exits, so that PV TLB flushes are used instead of IPIs). As requested on the list, also replace the existing VM_BUG_ON_PAGE() with a warning and bailout. Since the existing code only performed the BUG_ON check on DEBUG_VM kernels, ensure that the new code also only performs the check under that configuration - I don't want to mix two logically separate changes together too much. The macro VM_WARN_ON_ONCE_PAGE() doesn't return a value on !DEBUG_VM, so wrap the whole check in an #ifdef block. An alternative would be to change the VM_WARN_ON_ONCE_PAGE() definition for !DEBUG_VM such that it always returns false, but since that would differ from the behavior of the normal WARN macros, it might be too confusing for readers. Link: https://lkml.kernel.org/r/[email protected] Fixes: 7aef4172c795 ("mm: handle PTE-mapped tail pages in gerneric fast gup implementaiton") Signed-off-by: Jann Horn <[email protected]> Reviewed-by: John Hubbard <[email protected]> Cc: Matthew Wilcox <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Jan Kara <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-27Linux 5.13Linus Torvalds1-1/+1
2021-06-27Revert "signal: Allow tasks to cache one sigqueue struct"Linus Torvalds5-61/+2
This reverts commits 4bad58ebc8bc4f20d89cff95417c9b4674769709 (and 399f8dd9a866e107639eabd3c1979cd526ca3a98, which tried to fix it). I do not believe these are correct, and I'm about to release 5.13, so am reverting them out of an abundance of caution. The locking is odd, and appears broken. On the allocation side (in __sigqueue_alloc()), the locking is somewhat straightforward: it depends on sighand->siglock. Since one caller doesn't hold that lock, it further then tests 'sigqueue_flags' to avoid the case with no locks held. On the freeing side (in sigqueue_cache_or_free()), there is no locking at all, and the logic instead depends on 'current' being a single thread, and not able to race with itself. To make things more exciting, there's also the data race between freeing a signal and allocating one, which is handled by using WRITE_ONCE() and READ_ONCE(), and being mutually exclusive wrt the initial state (ie freeing will only free if the old state was NULL, while allocating will obviously only use the value if it was non-NULL, so only one or the other will actually act on the value). However, while the free->alloc paths do seem mutually exclusive thanks to just the data value dependency, it's not clear what the memory ordering constraints are on it. Could writes from the previous allocation possibly be delayed and seen by the new allocation later, causing logical inconsistencies? So it's all very exciting and unusual. And in particular, it seems that the freeing side is incorrect in depending on "current" being single-threaded. Yes, 'current' is a single thread, but in the presense of asynchronous events even a single thread can have data races. And such asynchronous events can and do happen, with interrupts causing signals to be flushed and thus free'd (for example - sending a SIGCONT/SIGSTOP can happen from interrupt context, and can flush previously queued process control signals). So regardless of all the other questions about the memory ordering and locking for this new cached allocation, the sigqueue_cache_or_free() assumptions seem to be fundamentally incorrect. It may be that people will show me the errors of my ways, and tell me why this is all safe after all. We can reinstate it if so. But my current belief is that the WRITE_ONCE() that sets the cached entry needs to be a smp_store_release(), and the READ_ONCE() that finds a cached entry needs to be a smp_load_acquire() to handle memory ordering correctly. And the sequence in sigqueue_cache_or_free() would need to either use a lock or at least be interrupt-safe some way (perhaps by using something like the percpu 'cmpxchg': it doesn't need to be SMP-safe, but like the percpu operations it needs to be interrupt-safe). Fixes: 399f8dd9a866 ("signal: Prevent sigqueue caching after task got released") Fixes: 4bad58ebc8bc ("signal: Allow tasks to cache one sigqueue struct") Cc: Thomas Gleixner <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Christian Brauner <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-26Merge tag 's390-5.13-5' of ↵Linus Torvalds5-21/+21
git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux Pull s390 fixes from Vasily Gorbik: - Fix a couple of late pt_regs flags handling findings of conversion to generic entry. - Fix potential register clobbering in stack switch helper. - Fix thread/group masks for offline cpus. - Fix cleanup of mdev resources when remove callback is invoked in vfio-ap code. * tag 's390-5.13-5' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390/stack: fix possible register corruption with stack switch helper s390/topology: clear thread/group maps for offline cpus s390/vfio-ap: clean up mdev resources when remove callback invoked s390: clear pt_regs::flags on irq entry s390: fix system call restart with multiple signals
2021-06-25Merge tag 'pinctrl-v5.13-3' of ↵Linus Torvalds2-3/+10
git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl Pull pin control fixes from Linus Walleij: "Two last-minute fixes: - Put an fwnode in the errorpath in the SGPIO driver - Fix the number of GPIO lines per bank in the STM32 driver" * tag 'pinctrl-v5.13-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: pinctrl: stm32: fix the reported number of GPIO lines per bank pinctrl: microchip-sgpio: Put fwnode in error case during ->probe()
2021-06-25Merge tag 'scsi-fixes' of ↵Linus Torvalds2-4/+20
git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi Pull SCSI fixes from James Bottomley: "Two small fixes, both in upper layer drivers (scsi disk and cdrom). The sd one is fixing a commit changing revalidation that came from the block tree a while ago (5.10) and the sr one adds handling of a condition we didn't previously handle for manually removed media" * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: scsi: sd: Call sd_revalidate_disk() for ioctl(BLKRRPART) scsi: sr: Return appropriate error code when disk is ejected
2021-06-25Merge branch 'akpm' (patches from Andrew)Linus Torvalds14-160/+258
Merge misc fixes from Andrew Morton: "24 patches, based on 4a09d388f2ab382f217a764e6a152b3f614246f6. Subsystems affected by this patch series: mm (thp, vmalloc, hugetlb, memory-failure, and pagealloc), nilfs2, kthread, MAINTAINERS, and mailmap" * emailed patches from Andrew Morton <[email protected]>: (24 commits) mailmap: add Marek's other e-mail address and identity without diacritics MAINTAINERS: fix Marek's identity again mm/page_alloc: do bulk array bounds check after checking populated elements mm/page_alloc: __alloc_pages_bulk(): do bounds check before accessing array mm/hwpoison: do not lock page again when me_huge_page() successfully recovers mm,hwpoison: return -EHWPOISON to denote that the page has already been poisoned mm/memory-failure: use a mutex to avoid memory_failure() races mm, futex: fix shared futex pgoff on shmem huge page kthread: prevent deadlock when kthread_mod_delayed_work() races with kthread_cancel_delayed_work_sync() kthread_worker: split code for canceling the delayed work timer mm/vmalloc: unbreak kasan vmalloc support KVM: s390: prepare for hugepage vmalloc mm/vmalloc: add vmalloc_no_huge nilfs2: fix memory leak in nilfs_sysfs_delete_device_group mm/thp: another PVMW_SYNC fix in page_vma_mapped_walk() mm/thp: fix page_vma_mapped_walk() if THP mapped by ptes mm: page_vma_mapped_walk(): get vma_address_end() earlier mm: page_vma_mapped_walk(): use goto instead of while (1) mm: page_vma_mapped_walk(): add a level of indentation mm: page_vma_mapped_walk(): crossing page table boundary ...
2021-06-25userfaultfd: uapi: fix UFFDIO_CONTINUE ioctl request definitionGleb Fotengauer-Malinovskiy1-2/+2
This ioctl request reads from uffdio_continue structure written by userspace which justifies _IOC_WRITE flag. It also writes back to that structure which justifies _IOC_READ flag. See NOTEs in include/uapi/asm-generic/ioctl.h for more information. Fixes: f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE ioctl") Signed-off-by: Gleb Fotengauer-Malinovskiy <[email protected]> Acked-by: Peter Xu <[email protected]> Reviewed-by: Axel Rasmussen <[email protected]> Reviewed-by: Dmitry V. Levin <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
2021-06-25Merge branch 'i2c/for-current' of ↵Linus Torvalds4-7/+16
git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux Pull i2c fixes from Wolfram Sang: "Three more driver bugfixes and an annotation fix for the core" * 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: i2c: robotfuzz-osif: fix control-request directions i2c: dev: Add __user annotation i2c: cp2615: check for allocation failure in cp2615_i2c_recv() i2c: i801: Ensure that SMBHSTSTS_INUSE_STS is cleared when leaving i801_access
2021-06-25Merge tag 'devprop-5.13-rc8' of ↵Linus Torvalds1-4/+12
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm Pull device properties framework fix from Rafael Wysocki: "Fix a NULL pointer dereference introduced by a recent commit and occurring when device_remove_software_node() is used with a device that has never been registered (Heikki Krogerus)" * tag 'devprop-5.13-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: software node: Handle software node injection to an existing device properly
2021-06-25Merge tag 'for-linus-5.13b-rc8-tag' of ↵Linus Torvalds1-1/+10
git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip Pull xen fix from Juergen Gross: "A fix for a regression introduced in 5.12: when migrating an irq related to a Xen user event to another cpu, a race might result in a WARN() triggering" * tag 'for-linus-5.13b-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip: xen/events: reset active flag for lateeoi events later
2021-06-25Merge tag 'for-linus-urgent' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds2-4/+19
Pull kvm fixes from Paolo Bonzini: "A selftests fix for ARM, and the fix for page reference count underflow. This is a very small fix that was provided by Nick Piggin and tested by myself" * tag 'for-linus-urgent' of git://git.kernel.org/pub/scm/virt/kvm/kvm: KVM: do not allow mapping valid but non-reference-counted pages KVM: selftests: Fix mapping length truncation in m{,un}map()
2021-06-25Merge tag 'x86_urgent_for_v5.13' of ↵Linus Torvalds3-43/+54
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 fixes from Borislav Petkov: "Two more urgent FPU fixes: - prevent unprivileged userspace from reinitializing supervisor states - prepare init_fpstate, which is the buffer used when initializing FPU state, properly in case the skip-writing-state-components XSAVE* variants are used" * tag 'x86_urgent_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu: Make init_fpstate correct with optimized XSAVE x86/fpu: Preserve supervisor states in sanitize_restored_user_xstate()
2021-06-25Merge tag 'ceph-for-5.13-rc8' of https://github.com/ceph/ceph-clientLinus Torvalds8-37/+50
Pull ceph fixes from Ilya Dryomov: "Two regression fixes from the merge window: one in the auth code affecting old clusters and one in the filesystem for proper propagation of MDS request errors. Also included a locking fix for async creates, marked for stable" * tag 'ceph-for-5.13-rc8' of https://github.com/ceph/ceph-client: libceph: set global_id as soon as we get an auth ticket libceph: don't pass result into ac->ops->handle_reply() ceph: fix error handling in ceph_atomic_open and ceph_lookup ceph: must hold snap_rwsem when filling inode for async create
2021-06-25Merge tag 'netfs-fixes-20210621' of ↵Linus Torvalds2-15/+45
git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs Pull netfs fixes from David Howells: "This contains patches to fix netfs_write_begin() and afs_write_end() in the following ways: (1) In netfs_write_begin(), extract the decision about whether to skip a page out to its own helper and have that clear around the region to be written, but not clear that region. This requires the filesystem to patch it up afterwards if the hole doesn't get completely filled. (2) Use offset_in_thp() in (1) rather than manually calculating the offset into the page. (3) Due to (1), afs_write_end() now needs to handle short data write into the page by generic_perform_write(). I've adopted an analogous approach to ceph of just returning 0 in this case and letting the caller go round again. It also adds a note that (in the future) the len parameter may extend beyond the page allocated. This is because the page allocation is deferred to write_begin() and that gets to decide what size of THP to allocate." Jeff Layton points out: "The netfs fix in particular fixes a data corruption bug in cephfs" * tag 'netfs-fixes-20210621' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: netfs: fix test for whether we can skip read when writing beyond EOF afs: Fix afs_write_end() to handle short writes