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aa6f8b2593
linux/mm
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John Hubbard aa6f8b2593 mm/gup: stop leaking pinned pages in low memory conditions 
If a driver tries to call any of the pin_user_pages*(FOLL_LONGTERM) family
of functions, and requests "too many" pages, then the call will
erroneously leave pages pinned.  This is visible in user space as an
actual memory leak.

Repro is trivial: just make enough pin_user_pages(FOLL_LONGTERM) calls to
exhaust memory.

The root cause of the problem is this sequence, within
__gup_longterm_locked():

    __get_user_pages_locked()
    rc = check_and_migrate_movable_pages()

...which gets retried in a loop.  The loop error handling is incomplete,
clearly due to a somewhat unusual and complicated tri-state error API. 
But anyway, if -ENOMEM, or in fact, any unexpected error is returned from
check_and_migrate_movable_pages(), then __gup_longterm_locked() happily
returns the error, while leaving the pages pinned.

In the failed case, which is an app that requests (via a device driver)
30720000000 bytes to be pinned, and then exits, I see this:

    $ grep foll /proc/vmstat
        nr_foll_pin_acquired 7502048
        nr_foll_pin_released 2048

And after applying this patch, it returns to balanced pins:

    $ grep foll /proc/vmstat
        nr_foll_pin_acquired 7502048
        nr_foll_pin_released 7502048

Note that the child routine, check_and_migrate_movable_folios(), avoids
this problem, by unpinning any folios in the **folios argument, before
returning an error.

Fix this by making check_and_migrate_movable_pages() behave in exactly the
same way as check_and_migrate_movable_folios(): unpin all pages in
**pages, before returning an error.

Also, documentation was an aggravating factor, so:

1) Consolidate the documentation for these two routines, now that they
have identical external behavior.

2) Rewrite the consolidated documentation:

    a) Clearly list the three return code cases, and what happens in
    each case.

    b) Mention that one of the cases unpins the pages or folios, before
    returning an error code.

Link: https://lkml.kernel.org/r/20241018223411.310331-1-jhubbard@nvidia.com
Fixes: 24a95998e9 ("mm/gup.c: simplify and fix check_and_migrate_movable_pages() return codes")
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Cc: Shigeru Yoshida <syoshida@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-10-30 20:14:10 -07:00
..
damon mm/damon/tests/sysfs-kunit.h: fix memory leak in damon_sysfs_test_add_targets() 2024-10-17 00:28:08 -07:00
kasan LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space 2024-10-21 22:11:19 +08:00
kfence mm: kfence: fix elapsed time for allocated/freed track 2024-09-26 14:01:44 -07:00
kmsan kmsan: do not pass NULL pointers as 0 2024-07-03 19:30:26 -07:00
backing-dev.c writeback: support retrieving per group debug writeback stats of bdi 2024-05-05 17:53:51 -07:00
balloon_compaction.c mm: remove MIGRATE_SYNC_NO_COPY mode 2024-07-03 19:30:00 -07:00
bootmem_info.c bootmem: use kmemleak_free_part_phys in put_page_bootmem 2023-10-25 16:47:13 -07:00
cma_debug.c
cma_sysfs.c mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
cma.c mm/cma: add cma_{alloc,free}_folio() 2024-09-03 21:15:36 -07:00
cma.h mm/cma: add sysfs file 'release_pages_success' 2024-02-22 10:24:57 -08:00
compaction.c mm:page_alloc: fix the NULL ac->nodemask in __alloc_pages_slowpath() 2024-09-03 21:15:47 -07:00
debug_page_alloc.c mm: page_alloc: consolidate free page accounting 2024-04-25 20:56:04 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm/debug_vm_pgtable: Use pxdp_get() for accessing page table entries 2024-09-17 01:07:01 -07:00
debug.c mm: support only one page_type per page 2024-09-03 21:15:43 -07:00
dmapool_test.c mm/dmapool: add MODULE_DESCRIPTION() 2024-07-03 19:29:58 -07:00
dmapool.c mm/mempool/dmapool: remove CONFIG_DEBUG_SLAB ifdefs 2023-12-05 11:17:58 +01:00
early_ioremap.c
execmem.c mm/execmem, arch: convert remaining overrides of module_alloc to execmem 2024-05-14 00:31:43 -07:00
fadvise.c introduce fd_file(), convert all accessors to it. 2024-08-12 22:00:43 -04:00
fail_page_alloc.c fault-inject: improve build for CONFIG_FAULT_INJECTION=n 2024-09-01 20:43:33 -07:00
failslab.c fault-inject: improve build for CONFIG_FAULT_INJECTION=n 2024-09-01 20:43:33 -07:00
filemap.c mm/filemap: fix filemap_get_folios_contig THP panic 2024-09-26 14:01:43 -07:00
folio-compat.c mm: remove putback_lru_page() 2024-09-09 16:38:59 -07:00
gup_test.c
gup_test.h
gup.c mm/gup: stop leaking pinned pages in low memory conditions 2024-10-30 20:14:10 -07:00
highmem.c mm/highmem: make nr_free_highpages() return "unsigned long" 2024-07-03 19:30:06 -07:00
hmm.c mm: provide mm_struct and address to huge_ptep_get() 2024-07-12 15:52:15 -07:00
huge_memory.c mm: huge_memory: add vma_thp_disabled() and thp_disabled_by_hw() 2024-10-17 00:28:10 -07:00
hugetlb_cgroup.c mm: memcg: don't call propagate_protected_usage() needlessly 2024-09-01 20:25:50 -07:00
hugetlb_vmemmap.c mm/hugetlb_vmemmap: don't synchronize_rcu() without HVO 2024-09-01 20:25:45 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: fix reference to nonexistent file 2023-10-25 16:47:14 -07:00
hugetlb.c mm/hugetlb: fix memfd_pin_folios resv_huge_pages leak 2024-09-26 14:01:43 -07:00
hwpoison-inject.c mm/hwpoison: add MODULE_DESCRIPTION() 2024-07-03 19:29:58 -07:00
init-mm.c mm: Deprecate pasid field 2023-12-12 10:11:32 +01:00
internal.h ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
interval_tree.c
io-mapping.c
ioremap.c
Kconfig resource: remove dependency on SPARSEMEM from GET_FREE_REGION 2024-10-28 21:40:39 -07:00
Kconfig.debug slub: Introduce CONFIG_SLUB_RCU_DEBUG 2024-08-27 14:12:51 +02:00
khugepaged.c mm: khugepaged: fix the incorrect statistics when collapsing large file folios 2024-10-17 00:28:10 -07:00
kmemleak.c mm/kmemleak: use IS_ERR_PCPU() for pointer in the percpu address space 2024-09-03 21:15:38 -07:00
ksm.c mm: remove PageSwapCache 2024-09-03 21:15:44 -07:00
list_lru.c mm: list_lru: fix UAF for memory cgroup 2024-08-07 18:33:56 -07:00
maccess.c
madvise.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
Makefile mm: introduce numa_emulation 2024-09-03 21:15:31 -07:00
mapping_dirty_helpers.c
memblock.c memblock: updates for 6.12-rc1 2024-09-25 11:35:19 -07:00
memcontrol-v1.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
memcontrol-v1.h memcg: cleanup with !CONFIG_MEMCG_V1 2024-09-17 01:07:00 -07:00
memcontrol.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
memfd.c mm/hugetlb: simplify refs in memfd_alloc_folio 2024-09-26 14:01:44 -07:00
memory_hotplug.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
memory-failure.c mm: migrate: add isolate_folio_to_list() 2024-09-03 21:15:59 -07:00
memory-tiers.c memory tiers: use default_dram_perf_ref_source in log message 2024-09-26 14:01:44 -07:00
memory.c mm: avoid unconditional one-tick sleep when swapcache_prepare fails 2024-10-28 21:40:41 -07:00
mempolicy.c mm,memcg: provide per-cgroup counters for NUMA balancing operations 2024-09-03 21:15:36 -07:00
mempool.c mm: fix xyz_noprof functions calling profiled functions 2024-06-05 19:19:26 -07:00
memremap.c mm: convert put_devmap_managed_page_refs() to put_devmap_managed_folio_refs() 2024-05-05 17:53:49 -07:00
memtest.c memtest: use {READ,WRITE}_ONCE in memory scanning 2024-03-13 12:12:21 -07:00
migrate_device.c mm: remap unused subpages to shared zeropage when splitting isolated thp 2024-09-09 16:39:03 -07:00
migrate.c mm: migrate: annotate data-race in migrate_folio_unmap() 2024-09-26 14:01:44 -07:00
mincore.c mm: provide mm_struct and address to huge_ptep_get() 2024-07-12 15:52:15 -07:00
mlock.c Random number generator updates for Linux 6.11-rc1. 2024-07-24 10:29:50 -07:00
mm_init.c mm: drop CONFIG_HAVE_ARCH_NODEDATA_EXTENSION 2024-09-03 21:15:28 -07:00
mm_slot.h
mmap_lock.c mm: mmap_lock: replace get_memcg_path_buf() with on-stack buffer 2024-07-03 19:30:26 -07:00
mmap.c mm: split critical region in remap_file_pages() and invoke LSMs in between 2024-10-28 21:40:41 -07:00
mmu_gather.c mm/mmu_gather: improve cond_resched() handling with large folios and expensive page freeing 2024-02-22 15:27:17 -08:00
mmu_notifier.c mm: move internal core VMA manipulation functions to own file 2024-09-01 20:25:54 -07:00
mmzone.c mm: improve code consistency with zonelist_* helper functions 2024-09-01 20:25:55 -07:00
mprotect.c mm/mprotect: replace can_modify_mm with can_modify_vma 2024-09-03 21:15:41 -07:00
mremap.c mm/mremap: fix move_normal_pmd/retract_page_tables race 2024-10-17 00:28:07 -07:00
mseal.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
msync.c
nommu.c mm: remove follow_page() 2024-09-01 20:26:01 -07:00
numa_emulation.c mm: introduce numa_emulation 2024-09-03 21:15:31 -07:00
numa_memblks.c mm: numa_clear_kernel_node_hotplug: Add NUMA_NO_NODE check for node id 2024-10-28 21:40:40 -07:00
numa.c mm: make range-to-target_node lookup facility a part of numa_memblks 2024-09-03 21:15:32 -07:00
oom_kill.c memory: remove the now superfluous sentinel element from ctl_table array 2024-04-25 20:56:32 -07:00
page_alloc.c mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves 2024-10-28 21:40:39 -07:00
page_counter.c mm, memcg: cg2 memory{.swap,}.peak write handlers 2024-09-01 20:25:53 -07:00
page_ext.c mm: don't account memmap per-node 2024-08-15 22:16:14 -07:00
page_idle.c
page_io.c mm: fix swap_read_folio_zeromap() for large folios with partial zeromap 2024-09-17 01:07:01 -07:00
page_isolation.c mm: remove migration for HugePage in isolate_single_pageblock() 2024-09-03 21:15:40 -07:00
page_owner.c mm/page-owner: use gfp_nested_mask() instead of open coded masking 2024-05-19 14:40:44 -07:00
page_poison.c mm/page_poison: replace kmap_atomic() with kmap_local_page() 2023-12-10 16:51:50 -08:00
page_reporting.c mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
page_reporting.h
page_table_check.c mm/page_table_check: fix crash on ZONE_DEVICE 2024-06-15 10:43:04 -07:00
page_vma_mapped.c mm: make page_mapped_in_vma conditional on CONFIG_MEMORY_FAILURE 2024-05-05 17:53:45 -07:00
page-writeback.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
pagewalk.c mm/pagewalk: fix usage of pmd_leaf()/pud_leaf() without present check 2024-10-28 21:40:38 -07:00
percpu-internal.h mm: remove CONFIG_MEMCG_KMEM 2024-07-10 12:14:54 -07:00
percpu-km.c
percpu-stats.c
percpu-vm.c percpu: clean up all mappings when pcpu_map_pages() fails 2024-04-25 20:55:49 -07:00
percpu.c percpu: remove pcpu_alloc_size() 2024-09-01 20:26:04 -07:00
pgalloc-track.h
pgtable-generic.c mm: fix race between __split_huge_pmd_locked() and GUP-fast 2024-05-07 10:37:00 -07:00
process_vm_access.c mm: fix process_vm_rw page counts 2023-12-10 16:51:39 -08:00
ptdump.c mm: ptdump: add check_wx_pages debugfs attribute 2024-02-22 10:24:47 -08:00
readahead.c struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
rmap.c mm: introduce a pageflag for partially mapped folios 2024-09-09 16:39:04 -07:00
rodata_test.c
secretmem.c secretmem: disable memfd_secret() if arch cannot set direct map 2024-10-09 12:47:19 -07:00
shmem_quota.c shmem_quota: build the object file conditionally to the config option 2024-09-01 20:25:45 -07:00
shmem.c mm: shmem: fix data-race in shmem_getattr() 2024-10-28 21:40:39 -07:00
show_mem.c mm/show_mem.c: report alloc tags in human readable units 2024-09-17 01:07:00 -07:00
shrinker_debug.c mm: shrinker: use min() to improve shrinker_debugfs_scan_write() 2024-09-03 21:15:40 -07:00
shrinker.c mm: shrinker: use kvzalloc_node() from expand_one_shrinker_info() 2024-01-05 09:58:32 -08:00
shuffle.c
shuffle.h mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER 2024-01-08 15:27:15 -08:00
slab_common.c mm, slab: suppress warnings in test_leak_destroy kunit test 2024-10-02 16:28:46 +02:00
slab.h mm, slab: suppress warnings in test_leak_destroy kunit test 2024-10-02 16:28:46 +02:00
slub.c mm, slab: suppress warnings in test_leak_destroy kunit test 2024-10-02 16:28:46 +02:00
sparse-vmemmap.c LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space 2024-10-21 22:11:19 +08:00
sparse.c A set of X86 fixes: 2024-09-01 14:43:08 -07:00
swap_cgroup.c mm: attempt to batch free swap entries for zap_pte_range() 2024-09-03 21:15:33 -07:00
swap_slots.c mm: swap: update get_swap_pages() to take folio order 2024-04-25 20:56:37 -07:00
swap_state.c mm: add nr argument in mem_cgroup_swapin_uncharge_swap() helper to support large folios 2024-09-17 01:07:01 -07:00
swap.c mm: remove isolate_lru_page() 2024-09-09 16:38:59 -07:00
swap.h mm: fix swap_read_folio_zeromap() for large folios with partial zeromap 2024-09-17 01:07:01 -07:00
swapfile.c mm/swapfile: skip HugeTLB pages for unuse_vma 2024-10-17 00:28:11 -07:00
truncate.c mm: Fix missing folio invalidation calls during truncation 2024-08-24 16:09:16 +02:00
usercopy.c
userfaultfd.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
util.c mm: only enforce minimum stack gap size if it's sensible 2024-09-01 20:26:02 -07:00
vma_internal.h mm: remove duplicated include in vma_internal.h 2024-09-01 20:26:02 -07:00
vma.c mm/vma: add expand-only VMA merge mode and optimise do_brk_flags() 2024-10-28 21:40:40 -07:00
vma.h mm/vma: add expand-only VMA merge mode and optimise do_brk_flags() 2024-10-28 21:40:40 -07:00
vmalloc.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
vmpressure.c eventfd: simplify eventfd_signal() 2023-11-28 14:08:38 +01:00
vmscan.c mm/mglru: only clear kswapd_failures if reclaimable 2024-10-17 00:28:12 -07:00
vmstat.c mm: split underused THPs 2024-09-09 16:39:04 -07:00
workingset.c cachestat: do not flush stats in recency check 2024-07-03 22:40:37 -07:00
z3fold.c mm/z3fold: add __percpu annotation to *unbuddied pointer in struct z3fold_pool 2024-09-01 20:25:56 -07:00
zbud.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zpool.c mm: zpool: return pool size in pages 2024-04-25 20:55:48 -07:00
zsmalloc.c ALong with the usual shower of singleton patches, notable patch series in 2024-09-21 07:29:05 -07:00
zswap.c mm: zswap: delete comments for "value" member of 'struct zswap_entry'. 2024-10-09 12:47:19 -07:00