Linus Torvalds f81fdd0c4a mm: document warning in move_normal_pmd() and make it warn only once ... Naresh Kamboju reported that the LTP tests can cause warnings on i386 going back all the way to v5.0, and bisected it to commit 2c91bd4a4e ("mm: speed up mremap by 20x on large regions"). The warning in move_normal_pmd() is actually mostly correct, but we have a very unusual special case at process creation time, when we may move the stack down with an overlapping mode (kind of like a "memmove()" except using the page tables). And when you have just the right condition of "move a large initial stack by the right alignment in the end, but with the early part of the move being only page-aligned", we'll be in a situation where we're trying to move a normal PMD entry on top of an already existing - but now empty - PMD entry. The warning is still worth having, in case it ever triggers other cases, and perhaps as a reminder that we could do the stack move case more efficiently (although it's clearly rare enough that it probably doesn't matter). But make it do WARN_ON_ONCE(), so that you can't flood the logs with it. And add a *big* comment above it to explain and remind us what's going on, because it took some figuring out to see how this could trigger. Kudos to Joel Fernandes for debugging this. Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Debugged-and-acked-by: Joel Fernandes <joel@joelfernandes.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2020-07-13 11:37:39 -07:00
..
kasan	mm: remove __ARCH_HAS_5LEVEL_HACK and include/asm-generic/5level-fixup.h	2020-06-04 19:06:21 -07:00
backing-dev.c
balloon_compaction.c
cleancache.c
cma_debug.c
cma.c	mm/cma.c: use exact_nid true to fix possible per-numa cma leak	2020-07-03 16:15:25 -07:00
cma.h
compaction.c	mm, compaction: make capture control handling safe wrt interrupts	2020-06-26 00:27:36 -07:00
debug_page_ref.c
debug_vm_pgtable.c	mm/debug_vm_pgtable: fix build failure with powerpc 8xx	2020-06-26 00:27:37 -07:00
debug.c	maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault	2020-06-17 10:57:41 -07:00
dmapool.c
early_ioremap.c
fadvise.c
failslab.c
filemap.c	fs: Add IOCB_NOIO flag for generic_file_read_iter	2020-07-07 23:40:08 +02:00
frame_vector.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
frontswap.c	mm/frontswap: fix some typos in frontswap.c	2020-06-04 19:06:24 -07:00
gup_benchmark.c
gup.c	mm: Allow arches to provide ptep_get()	2020-06-20 22:14:53 +10:00
highmem.c
hmm.c	mmap locking API: add mmap_assert_locked() and mmap_assert_write_locked()	2020-06-09 09:39:14 -07:00
huge_memory.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
hugetlb_cgroup.c
hugetlb.c	mm/hugetlb.c: fix pages per hugetlb calculation	2020-07-03 16:15:25 -07:00
hwpoison-inject.c
init-mm.c	mmap locking API: add MMAP_LOCK_INITIALIZER	2020-06-09 09:39:14 -07:00
internal.h	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
interval_tree.c
Kconfig	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next	2020-06-07 17:25:29 -07:00
Kconfig.debug	treewide: replace '---help---' in Kconfig files with 'help'	2020-06-14 01:57:21 +09:00
khugepaged.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
kmemleak-test.c
kmemleak.c
ksm.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
list_lru.c	mm/list_lru: fix a typo in comment "numbesr"->"numbers"	2020-06-04 19:06:24 -07:00
maccess.c	maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault	2020-06-17 10:57:41 -07:00
madvise.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
Makefile	The Kernel Concurrency Sanitizer (KCSAN)	2020-06-11 18:55:43 -07:00
mapping_dirty_helpers.c
memblock.c	mm/memblock: fix a typo in comment "implict"->"implicit"	2020-06-04 19:06:23 -07:00
memcontrol.c	mm/memcontrol.c: prevent missed memory.low load tears	2020-06-26 00:27:37 -07:00
memfd.c
memory_hotplug.c	mm/memory_hotplug.c: fix false softlockup during pfn range removal	2020-06-26 00:27:38 -07:00
memory-failure.c	mm/memory-failure: send SIGBUS(BUS_MCEERR_AR) only to current thread	2020-06-11 18:17:47 -07:00
memory.c	mm/memory: fix IO cost for anonymous page	2020-06-26 00:27:38 -07:00
mempolicy.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
mempool.c
memremap.c
memtest.c
migrate.c	Raise gcc version requirement to 4.9	2020-07-08 10:48:35 -07:00
mincore.c	mmap locking API: use coccinelle to convert mmap_sem rwsem call sites	2020-06-09 09:39:14 -07:00
mlock.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
mm_init.c
mmap.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
mmu_gather.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
mmu_notifier.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
mmzone.c
mprotect.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
mremap.c	mm: document warning in move_normal_pmd() and make it warn only once	2020-07-13 11:37:39 -07:00
msync.c	mmap locking API: use coccinelle to convert mmap_sem rwsem call sites	2020-06-09 09:39:14 -07:00
nommu.c	mm: remove vmalloc_exec	2020-06-26 00:27:38 -07:00
oom_kill.c	kernel: better document the use_mm/unuse_mm API contract	2020-06-10 19:14:18 -07:00
page_alloc.c	mm/page_alloc: fix documentation error	2020-07-03 16:15:25 -07:00
page_counter.c
page_ext.c
page_idle.c	mm/page_idle.c: skip offline pages	2020-06-08 11:05:55 -07:00
page_io.c	mm: don't include asm/pgtable.h if linux/mm.h is already included	2020-06-09 09:39:13 -07:00
page_isolation.c	mm: Allow to offline unmovable PageOffline() pages via MEM_GOING_OFFLINE	2020-06-04 15:36:52 -04:00
page_owner.c
page_poison.c
page_reporting.c
page_reporting.h	mm: introduce include/linux/pgtable.h	2020-06-09 09:39:13 -07:00
page_vma_mapped.c
page-writeback.c	mm/page-writeback: fix a typo in comment "effictive"->"effective"	2020-06-04 19:06:24 -07:00
pagewalk.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
percpu-internal.h
percpu-km.c
percpu-stats.c
percpu-vm.c
percpu.c
pgtable-generic.c	mm: introduce include/linux/pgtable.h	2020-06-09 09:39:13 -07:00
process_vm_access.c	mmap locking API: use coccinelle to convert mmap_sem rwsem call sites	2020-06-09 09:39:14 -07:00
ptdump.c	mmap locking API: use coccinelle to convert mmap_sem rwsem call sites	2020-06-09 09:39:14 -07:00
readahead.c
rmap.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
rodata_test.c	maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault	2020-06-17 10:57:41 -07:00
shmem.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
shuffle.c
shuffle.h
slab_common.c	mm/slab: use memzero_explicit() in kzfree()	2020-06-26 00:27:37 -07:00
slab.c
slab.h	mm, slab: fix sign conversion problem in memcg_uncharge_slab()	2020-06-26 00:27:37 -07:00
slob.c
slub.c	slub: cure list_slab_objects() from double fix	2020-06-26 00:27:37 -07:00
sparse-vmemmap.c	mm: don't include asm/pgtable.h if linux/mm.h is already included	2020-06-09 09:39:13 -07:00
sparse.c	mm: don't include asm/pgtable.h if linux/mm.h is already included	2020-06-09 09:39:13 -07:00
swap_cgroup.c
swap_slots.c
swap_state.c	mm: fix swap cache node allocation mask	2020-06-26 00:27:37 -07:00
swap.c	mm/swap: fix for "mm: workingset: age nonresident information alongside anonymous pages"	2020-06-26 00:27:38 -07:00
swapfile.c	mmap locking API: use coccinelle to convert mmap_sem rwsem call sites	2020-06-09 09:39:14 -07:00
truncate.c
usercopy.c
userfaultfd.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
util.c	mmap locking API: convert mmap_sem comments	2020-06-09 09:39:14 -07:00
vmacache.c	kernel: better document the use_mm/unuse_mm API contract	2020-06-10 19:14:18 -07:00
vmalloc.c	mm: remove vmalloc_exec	2020-06-26 00:27:38 -07:00
vmpressure.c
vmscan.c	mm: workingset: age nonresident information alongside anonymous pages	2020-06-26 00:27:37 -07:00
vmstat.c	mm/vmstat.c: convert to use DEFINE_SEQ_ATTRIBUTE macro	2020-06-04 19:06:26 -07:00
workingset.c	mm: workingset: age nonresident information alongside anonymous pages	2020-06-26 00:27:37 -07:00
z3fold.c
zbud.c	mm: use false for bool variable	2020-06-04 19:06:24 -07:00
zpool.c
zsmalloc.c	mm: reorder includes after introduction of linux/pgtable.h	2020-06-09 09:39:13 -07:00
zswap.c