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Linus Torvalds 6cd06ab12d gup: make the stack expansion warning a bit more targeted 
I added a warning about about GUP no longer expanding the stack in
commit a425ac5365 ("gup: add warning if some caller would seem to want
stack expansion"), but didn't really expect anybody to hit it.

And it's true that nobody seems to have hit a _real_ case yet, but we
certainly have a number of reports of false positives.  Which not only
causes extra noise in itself, but might also end up hiding any real
cases if they do exist.

So let's tighten up the warning condition, and replace the simplistic

	vma = find_vma(mm, start);
	if (vma && (start < vma->vm_start)) {
		WARN_ON_ONCE(vma->vm_flags & VM_GROWSDOWN);

with a

	vma = gup_vma_lookup(mm, start);

helper function which works otherwise like just "vma_lookup()", but with
some heuristics for when to warn about gup no longer causing stack
expansion.

In particular, don't just warn for "below the stack", but warn if it's
_just_ below the stack (with "just below" arbitrarily defined as 64kB,
because why not?).  And rate-limit it to at most once per hour, which
means that any false positives shouldn't completely hide subsequent
reports, but we won't be flooding the logs about it either.

The previous code triggered when some GUP user (chromium crashpad)
accessing past the end of the previous vma, for example.  That has never
expanded the stack, it just causes GUP to return early, and as such we
shouldn't be warning about it.

This is still going trigger the randomized testers, but to mitigate the
noise from that, use "dump_stack()" instead of "WARN_ON_ONCE()" to get
the kernel call chain.  We'll get the relevant information, but syzbot
shouldn't get too upset about it.

Also, don't even bother with the GROWSUP case, which would be using
different heuristics entirely, but only happens on parisc.

Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: John Hubbard <jhubbard@nvidia.com>
Reported-by: syzbot+6cf44e127903fdf9d929@syzkaller.appspotmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2023-07-05 09:33:31 -07:00
..
damon Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-06-23 16:58:19 -07:00
kasan kasan,kmsan: remove __GFP_KSWAPD_RECLAIM usage from kasan/kmsan 2023-06-23 16:59:26 -07:00
kfence mm/slab: introduce kmem_cache flag SLAB_NO_MERGE 2023-06-02 10:24:33 +02:00
kmsan kasan,kmsan: remove __GFP_KSWAPD_RECLAIM usage from kasan/kmsan 2023-06-23 16:59:26 -07:00
Kconfig slab updates for 6.5 2023-06-29 16:34:12 -07:00
Kconfig.debug mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM 2023-05-29 16:14:28 +01:00
Makefile mm: page_alloc: split out DEBUG_PAGEALLOC 2023-06-09 16:25:23 -07:00
backing-dev.c mm: backing-dev: make bdi_class a static const structure 2023-06-23 16:59:27 -07:00
balloon_compaction.c
…
bootmem_info.c
…
cma.c mm/page_owner/cma: show pfn in cma/page_owner with hex format 2023-06-19 16:19:32 -07:00
cma.h
…
cma_debug.c
…
cma_sysfs.c mm: cma: make kobj_type structure constant 2023-03-28 16:20:06 -07:00
compaction.c mm: compaction: convert to use a folio in isolate_migratepages_block() 2023-06-23 16:59:31 -07:00
debug.c mm: update validate_mm() to use vma iterator 2023-06-09 16:25:31 -07:00
debug_page_alloc.c mm: page_alloc: split out DEBUG_PAGEALLOC 2023-06-09 16:25:23 -07:00
debug_page_ref.c
…
debug_vm_pgtable.c mm/debug_vm_pgtable,page_table_check: warn pte map fails 2023-06-19 16:19:15 -07:00
dmapool.c dmapool: create/destroy cleanup 2023-06-09 16:25:17 -07:00
dmapool_test.c dmapool: add alloc/free performance test 2023-04-05 19:42:38 -07:00
early_ioremap.c mm/early_ioremap.c: improve the execution efficiency of early_ioremap_setup() 2023-06-09 16:25:56 -07:00
fadvise.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
fail_page_alloc.c mm: page_alloc: split out FAIL_PAGE_ALLOC 2023-06-09 16:25:23 -07:00
failslab.c
…
filemap.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
folio-compat.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
frontswap.c mm: zswap: support exclusive loads 2023-06-19 16:19:05 -07:00
gup.c gup: make the stack expansion warning a bit more targeted 2023-07-05 09:33:31 -07:00
gup_test.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-06-23 16:58:19 -07:00
gup_test.h
…
highmem.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
hmm.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
huge_memory.c mm: remove references to pagevec 2023-06-23 16:59:30 -07:00
hugetlb.c hugetlb: revert use of page_cache_next_miss() 2023-06-23 16:59:32 -07:00
hugetlb_cgroup.c mm/hugetlb: increase use of folios in alloc_huge_page() 2023-02-13 15:54:27 -08:00
hugetlb_vmemmap.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
hugetlb_vmemmap.h
…
hwpoison-inject.c
…
init-mm.c IOMMU Updates for Linux 6.4 2023-04-30 13:00:38 -07:00
internal.h - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
interval_tree.c
…
io-mapping.c
…
ioremap.c
…
khugepaged.c mm/khugepaged: fix regression in collapse_file() 2023-06-29 09:41:45 -07:00
kmemleak.c lib/stackdepot, mm: rename stack_depot_want_early_init 2023-02-16 20:43:49 -08:00
ksm.c mm: remove references to pagevec 2023-06-23 16:59:30 -07:00
list_lru.c
…
maccess.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
madvise.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
mapping_dirty_helpers.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
memblock.c memblock: small updates for 6.5-rc1 2023-06-29 23:21:20 -07:00
memcontrol.c mm/memcontrol: do not tweak node in mem_cgroup_init() 2023-06-23 16:59:26 -07:00
memfd.c memfd: check for non-NULL file_seals in memfd_create() syscall 2023-06-19 13:19:31 -07:00
memory-failure.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
memory-tiers.c memory tier: remove unneeded !IS_ENABLED(CONFIG_MIGRATION) check 2023-06-19 16:19:29 -07:00
memory.c gup: avoid stack expansion warning for known-good case 2023-06-29 12:36:47 -07:00
memory_hotplug.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
mempolicy.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
mempool.c
…
memremap.c
…
memtest.c mm/memtest: add results of early memtest to /proc/meminfo 2023-04-05 19:42:55 -07:00
migrate.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
migrate_device.c mm: remove references to pagevec 2023-06-23 16:59:30 -07:00
mincore.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
mlock.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
mm_init.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
mm_slot.h
…
mmap.c mm: don't do validate_mm() unnecessarily and without mmap locking 2023-07-04 07:22:59 -07:00
mmap_lock.c
…
mmu_gather.c mm: prefer xxx_page() alloc/free functions for order-0 pages 2023-03-28 16:20:16 -07:00
mmu_notifier.c
…
mmzone.c
…
mprotect.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-06-23 16:58:19 -07:00
mremap.c mm: Update do_vmi_align_munmap() return semantics 2023-07-01 08:10:56 -07:00
msync.c
…
nommu.c xtensa: fix lock_mm_and_find_vma in case VMA not found 2023-07-01 08:00:05 -07:00
oom_kill.c mm, oom: do not check 0 mask in out_of_memory() 2023-06-09 16:25:20 -07:00
page-writeback.c mm: kill lock|unlock_page_memcg() 2023-06-19 16:19:33 -07:00
page_alloc.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
page_counter.c
…
page_ext.c
…
page_idle.c
…
page_io.c swap: use __bio_add_page to add page to bio 2023-05-31 09:50:02 -06:00
page_isolation.c mm: page_isolation: write proper kerneldoc 2023-06-19 16:18:59 -07:00
page_owner.c mm/page_owner/cma: show pfn in cma/page_owner with hex format 2023-06-19 16:19:32 -07:00
page_poison.c
…
page_reporting.c mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
page_reporting.h
…
page_table_check.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
page_vma_mapped.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
pagewalk.c mm/pagewalk: walk_pte_range() allow for pte_offset_map() 2023-06-19 16:19:14 -07:00
percpu-internal.h percpu-internal/pcpu_chunk: re-layout pcpu_chunk structure to reduce false sharing 2023-06-19 16:19:29 -07:00
percpu-km.c
…
percpu-stats.c
…
percpu-vm.c
…
percpu.c mm: memcontrol: rename memcg_kmem_enabled() 2023-02-16 20:43:56 -08:00
pgalloc-track.h
…
pgtable-generic.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
process_vm_access.c mm/gup: remove unused vmas parameter from pin_user_pages_remote() 2023-06-09 16:25:25 -07:00
ptdump.c mm: ptdump should use ptep_get_lockless() 2023-06-19 16:19:24 -07:00
readahead.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
rmap.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
rodata_test.c
…
secretmem.c mm/mlock: rename mlock_future_check() to mlock_future_ok() 2023-06-09 16:25:38 -07:00
shmem.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
show_mem.c mm: page_alloc: collect mem statistic into show_mem.c 2023-06-09 16:25:22 -07:00
shrinker_debug.c Revert "mm: shrinkers: make count and scan in shrinker debugfs lockless" 2023-06-19 13:19:34 -07:00
shuffle.c
…
shuffle.h mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
slab.c slab updates for 6.5 2023-06-29 16:34:12 -07:00
slab.h slab updates for 6.5 2023-06-29 16:34:12 -07:00
slab_common.c slab updates for 6.5 2023-06-29 16:34:12 -07:00
slub.c slab updates for 6.5 2023-06-29 16:34:12 -07:00
sparse-vmemmap.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
sparse.c - Arnd Bergmann has fixed a bunch of -Wmissing-prototypes in 2023-06-28 10:59:38 -07:00
swap.c mm: remove references to pagevec 2023-06-23 16:59:30 -07:00
swap.h
…
swap_cgroup.c
…
swap_slots.c
…
swap_state.c mm: remove unnecessary pagevec includes 2023-06-23 16:59:31 -07:00
swapfile.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
truncate.c mm: remove references to pagevec 2023-06-23 16:59:30 -07:00
usercopy.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
userfaultfd.c mm: ptep_get() conversion 2023-06-19 16:19:25 -07:00
util.c mm: uninline kstrdup() 2023-04-08 13:45:37 -07:00
vmalloc.c Merge mm-hotfixes-stable into mm-stable to pick up depended-upon changes. 2023-06-23 16:58:19 -07:00
vmpressure.c
…
vmscan.c mm/vmscan: fix root proactive reclaim unthrottling unbalanced node 2023-06-23 16:59:32 -07:00
vmstat.c - Yosry Ahmed brought back some cgroup v1 stats in OOM logs. 2023-06-28 10:28:11 -07:00
workingset.c Multi-gen LRU: fix workingset accounting 2023-06-09 16:25:46 -07:00
z3fold.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zbud.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zpool.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zsmalloc.c mm: zswap: remove shrink from zpool interface 2023-06-19 16:19:27 -07:00
zswap.c mm: zswap: fix double invalidate with exclusive loads 2023-06-23 16:59:31 -07:00