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Linus Torvalds 4057527a5e mm: make page ref count overflow check tighter and more explicit 
commit f958d7b528b1b40c44cfda5eabe2d82760d868c3 upsteam.

We have a VM_BUG_ON() to check that the page reference count doesn't
underflow (or get close to overflow) by checking the sign of the count.

That's all fine, but we actually want to allow people to use a "get page
ref unless it's already very high" helper function, and we want that one
to use the sign of the page ref (without triggering this VM_BUG_ON).

Change the VM_BUG_ON to only check for small underflows (or _very_ close
to overflowing), and ignore overflows which have strayed into negative
territory.

Acked-by: Matthew Wilcox <willy@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ 4.4.y backport notes:
  Ajay: Open-coded atomic refcount access due to missing
  page_ref_count() helper in 4.4.y
  Srivatsa: Added overflow check to get_page_foll() and related code. ]
Signed-off-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Signed-off-by: Ajay Kaher <akaher@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-11 07:51:15 +01:00
..
kasan
kasan: fix shadow_size calculation error in kasan_module_alloc
2018-08-24 13:26:58 +02:00
backing-dev.c
writeback: synchronize sync(2) against cgroup writeback membership switches
2019-06-11 12:23:41 +02:00
balloon_compaction.c
virtio_balloon: fix race between migration and ballooning
2016-03-03 15:07:18 -08:00
bootmem.c
bootmem: avoid freeing to bootmem after bootmem is done
2015-09-08 15:35:28 -07:00
cleancache.c
cleancache: remove limit on the number of cleancache enabled filesystems
2015-04-14 16:49:03 -07:00
cma_debug.c
mm/cma_debug.c: fix the break condition in cma_maxchunk_get()
2019-06-22 08:18:18 +02:00
cma.c
mm/cma.c: fail if fixed declaration can't be honored
2019-08-06 18:28:27 +02:00
cma.h
mm: cma: mark cma_bitmap_maxno() inline in header
2015-08-14 15:56:32 -07:00
compaction.c
mm/compaction: pass only pageblock aligned range to pageblock_pfn_to_page
2018-01-17 09:35:26 +01:00
debug-pagealloc.c
mm, hwpoison: fixup "mm: check the return value of lookup_page_ext for all call sites"
2017-11-24 11:26:29 +01:00
debug.c
mm: get rid of vmacache_flush_all() entirely
2018-09-19 22:49:00 +02:00
dmapool.c
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
2015-11-06 17:50:42 -08:00
early_ioremap.c
mm/early_ioremap: Fix boot hang with earlyprintk=efi,keep
2018-02-25 11:03:41 +01:00
fadvise.c
mm/fadvise.c: fix signed overflow UBSAN complaint
2018-09-15 09:40:38 +02:00
failslab.c
mm, page_alloc: rename __GFP_WAIT to __GFP_RECLAIM
2015-11-06 17:50:42 -08:00
filemap.c
mm/filemap.c: don't initiate writeback if mapping has no dirty pages
2019-11-12 19:13:30 +01:00
frame_vector.c
mm: replace get_vaddr_frames() write/force parameters with gup_flags
2018-12-17 21:55:16 +01:00
frontswap.c
frontswap: allow multiple backends
2015-06-24 17:49:45 -07:00
gup.c
proc: do not access cmdline nor environ from file-backed areas
2018-12-17 21:55:17 +01:00
highmem.c
mm/highmem: make kmap cache coloring aware
2014-08-06 18:01:22 -07:00
huge_memory.c
mremap: properly flush TLB before releasing the page
2018-11-10 07:41:42 -08:00
hugetlb_cgroup.c
mm: hugetlb: switch to css_tryget() in hugetlb_cgroup_charge_cgroup()
2019-11-25 15:53:43 +01:00
hugetlb.c
hugetlbfs: on restore reserve error path retain subpool reservation
2019-06-22 08:18:17 +02:00
hwpoison-inject.c
hwpoison: use page_cgroup_ino for filtering by memcg
2015-09-10 13:29:01 -07:00
init-mm.c
mm: Add a user_ns owner to mm_struct and fix ptrace permission checks
2017-01-06 11:16:11 +01:00
internal.h
mm: make page ref count overflow check tighter and more explicit
2020-03-11 07:51:15 +01:00
interval_tree.c
mm: replace vma->sharead.linear with vma->shared
2015-02-10 14:30:31 -08:00
Kconfig
mm: don't allow deferred pages with NEED_PER_CPU_KM
2018-05-26 08:48:55 +02:00
Kconfig.debug
mm/debug_pagealloc: remove obsolete Kconfig options
2015-01-08 15:10:52 -08:00
kmemcheck.c
mm/slab_common: move kmem_cache definition to internal header
2014-10-09 22:25:50 -04:00
kmemleak-test.c
mm/kmemleak-test.c: use pr_fmt for logging
2014-06-06 16:08:18 -07:00
kmemleak.c
mm/kmemleak.c: fix check for softirq context
2019-08-04 09:34:59 +02:00
ksm.c
mm/ksm.c: don't WARN if page is still mapped in remove_stable_node()
2019-11-28 18:25:27 +01:00
list_lru.c
mm/list_lru.c: fix memory leak in __memcg_init_list_lru_node
2019-06-22 08:18:22 +02:00
maccess.c
mm/maccess.c: actually return -EFAULT from strncpy_from_unsafe
2015-11-05 19:34:48 -08:00
madvise.c
mm: madvise(MADV_DODUMP): allow hugetlbfs pages
2018-10-10 08:52:11 +02:00
Makefile
media updates for v4.3-rc1
2015-09-11 16:42:39 -07:00
memblock.c
mm: consider memblock reservations for deferred memory initialization sizing
2017-06-14 13:16:26 +02:00
memcontrol.c
mm: memcg: switch to css_tryget() in get_mem_cgroup_from_mm()
2019-11-25 15:53:43 +01:00
memory_hotplug.c
mm, memory_hotplug: test_pages_in_a_zone do not pass the end of zone
2019-03-23 08:44:26 +01:00
memory-failure.c
hwpoison, memcg: forcibly uncharge LRU pages
2018-01-31 12:06:09 +01:00
memory.c
mm: replace access_remote_vm() write parameter with gup_flags
2018-12-17 21:55:17 +01:00
mempolicy.c
mm/mempolicy.c: fix out of bounds write in mpol_parse_str()
2020-02-05 13:03:38 +00:00
mempool.c
mm/mempool: avoid KASAN marking mempool poison checks as use-after-free
2017-08-12 19:29:09 -07:00
memtest.c
memtest: remove unused header files
2015-09-08 15:35:28 -07:00
migrate.c
hugetlbfs: fix races and page leaks during migration
2019-03-23 08:44:23 +01:00
mincore.c
mm/mincore.c: make mincore() more conservative
2019-06-11 12:23:36 +02:00
mlock.c
mm: mlock: avoid increase mm->locked_vm on mlock() when already mlock2(,MLOCK_ONFAULT)
2018-12-13 09:21:33 +01:00
mm_init.c
mm: meminit: remove mminit_verify_page_links
2015-06-30 19:44:56 -07:00
mmap.c
coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping
2019-06-22 08:18:27 +02:00
mmu_context.c
mm/mmu_context, sched/core: Fix mmu_context.h assumption
2017-12-25 14:22:09 +01:00
mmu_notifier.c
mm/mmu_notifier: use hlist_add_head_rcu()
2019-08-04 09:34:59 +02:00
mmzone.c
mm: microoptimize zonelist operations
2015-02-11 17:06:02 -08:00
mprotect.c
x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings
2018-08-15 17:42:10 +02:00
mremap.c
mremap: properly flush TLB before releasing the page
2018-11-10 07:41:42 -08:00
msync.c
mm/msync: use offset_in_page macro
2015-11-05 19:34:48 -08:00
nobootmem.c
mm: page_alloc: pass PFN to __free_pages_bootmem
2015-06-30 19:44:55 -07:00
nommu.c
mm: replace access_remote_vm() write parameter with gup_flags
2018-12-17 21:55:17 +01:00
oom_kill.c
mm, oom: fix use-after-free in oom_kill_process
2019-02-06 19:43:07 +01:00
page_alloc.c
mm/page_alloc.c: calculate 'available' memory in a separate function
2020-01-23 08:18:35 +01:00
page_counter.c
mm: page_counter: let page_counter_try_charge() return bool
2015-11-05 19:34:48 -08:00
page_ext.c
mm/page_ext.c: fix an imbalance with kmemleak
2019-04-27 09:33:48 +02:00
page_idle.c
mm/page_idle.c: fix oops because end_pfn is larger than max_pfn
2019-07-10 09:56:30 +02:00
page_io.c
fs: use helper bio_add_page() instead of open coding on bi_io_vec
2015-08-13 12:32:00 -06:00
page_isolation.c
mm: fix invalid node in alloc_migrate_target()
2016-04-20 15:41:53 +09:00
page_owner.c
mm: check the return value of lookup_page_ext for all call sites
2017-11-24 08:32:25 +01:00
page-writeback.c
mm/page-writeback.c: avoid potential division by zero in wb_min_max_ratio()
2020-01-23 08:18:39 +01:00
pagewalk.c
mm/pagewalk.c: report holes in hugetlb ranges
2017-11-24 08:32:25 +01:00
percpu-km.c
percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated
2014-09-02 14:46:05 -04:00
percpu-vm.c
percpu: move region iterations out of pcpu_[de]populate_chunk()
2014-09-02 14:46:02 -04:00
percpu.c
percpu: include linux/sched.h for cond_resched()
2018-05-16 10:06:46 +02:00
pgtable-generic.c
mm,thp: khugepaged: call pte flush at the time of collapse
2016-02-25 12:01:23 -08:00
process_vm_access.c
mm: replace get_user_pages_unlocked() write/force parameters with gup_flags
2018-12-17 21:55:16 +01:00
quicklist.c
…
readahead.c
mm, fs: introduce mapping_gfp_constraint()
2015-11-06 17:50:42 -08:00
rmap.c
mm/rmap: replace BUG_ON(anon_vma->degree) with VM_WARN_ON
2019-04-03 06:23:18 +02:00
shmem.c
mm/shmem.c: cast the type of unmap_start to u64
2019-12-21 10:35:36 +01:00
slab_common.c
slub: do not merge cache if slub_debug contains a never-merge flag
2017-10-21 17:09:05 +02:00
slab.c
mm/slab.c: kmemleak no scan alien caches
2019-04-27 09:33:48 +02:00
slab.h
slab/slub: adjust kmem_cache_alloc_bulk API
2015-11-22 11:58:44 -08:00
slob.c
slab/slub: adjust kmem_cache_alloc_bulk API
2015-11-22 11:58:44 -08:00
slub.c
mm/slub: fix a deadlock in show_slab_objects()
2019-10-29 09:13:28 +01:00
sparse-vmemmap.c
…
sparse.c
…
swap_cgroup.c
mm, swap_cgroup: reschedule when neeed in swap_cgroup_swapoff()
2017-07-05 14:37:15 +02:00
swap_state.c
mm: swap: zswap: maybe_preload & refactoring
2015-09-08 15:35:28 -07:00
swap.c
mm: make compound_head() robust
2015-11-06 17:50:42 -08:00
swapfile.c
x86/speculation/l1tf: Limit swap file size to MAX_PA/2
2018-08-15 17:42:10 +02:00
truncate.c
mm: cleancache: fix corruption on missed inode invalidation
2018-12-13 09:21:33 +01:00
userfaultfd.c
userfaultfd: avoid mmap_sem read recursion in mcopy_atomic
2015-09-04 16:54:41 -07:00
util.c
mm: replace get_user_pages_unlocked() write/force parameters with gup_flags
2018-12-17 21:55:16 +01:00
vmacache.c
mm: get rid of vmacache_flush_all() entirely
2018-09-19 22:49:00 +02:00
vmalloc.c
mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()
2019-08-25 10:52:44 +02:00
vmpressure.c
mm: vmpressure: fix sending wrong events on underflow
2017-03-12 06:37:25 +01:00
vmscan.c
mm: fix the NULL mapping case in __isolate_lru_page()
2018-06-06 16:46:23 +02:00
vmstat.c
mm, vmstat: hide /proc/pagetypeinfo from normal users
2019-11-12 19:13:18 +01:00
workingset.c
mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()
2016-10-28 03:01:34 -04:00
zbud.c
mm: zsmalloc: constify struct zs_pool name
2015-11-06 17:50:42 -08:00
zpool.c
mm: zsmalloc: constify struct zs_pool name
2015-11-06 17:50:42 -08:00
zsmalloc.c
zsmalloc: fix zs_can_compact() integer overflow
2016-05-18 17:06:44 -07:00
zswap.c
zswap: re-check zswap_is_full() after do zswap_shrink()
2018-09-05 09:18:36 +02:00