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linux-stable/mm
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Vlastimil Babka 63931eb975 mm, page_alloc: disallow __GFP_COMP in alloc_pages_exact() 
alloc_pages_exact*() allocates a page of sufficient order and then splits
it to return only the number of pages requested.  That makes it
incompatible with __GFP_COMP, because compound pages cannot be split.

As shown by [1] things may silently work until the requested size
(possibly depending on user) stops being power of two.  Then for
CONFIG_DEBUG_VM, BUG_ON() triggers in split_page().  Without
CONFIG_DEBUG_VM, consequences are unclear.

There are several options here, none of them great:

1) Don't do the splitting when __GFP_COMP is passed, and return the
   whole compound page.  However if caller then returns it via
   free_pages_exact(), that will be unexpected and the freeing actions
   there will be wrong.

2) Warn and remove __GFP_COMP from the flags.  But the caller may have
   really wanted it, so things may break later somewhere.

3) Warn and return NULL.  However NULL may be unexpected, especially
   for small sizes.

This patch picks option 2, because as Michal Hocko put it: "callers wanted
it" is much less probable than "caller is simply confused and more gfp
flags is surely better than fewer".

[1] https://lore.kernel.org/lkml/20181126002805.GI18977@shao2-debian/T/#u

Link: http://lkml.kernel.org/r/0c6393eb-b28d-4607-c386-862a71f09de6@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 09:47:45 -07:00
..
kasan arm64 updates for 5.2 2019-05-06 17:54:22 -07:00
backing-dev.c writeback: synchronize sync(2) against cgroup writeback membership switches 2019-01-22 14:39:38 -07:00
balloon_compaction.c virtio_balloon: fix deadlock on OOM 2017-11-14 23:57:38 +02:00
cleancache.c mm: use octal not symbolic permissions 2018-06-15 07:55:25 +09:00
cma.c memblock: emphasize that memblock_alloc_range() returns a physical address 2019-03-12 10:04:01 -07:00
cma.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cma_debug.c mm/cma_debug.c: fix the break condition in cma_maxchunk_get() 2019-05-14 09:47:45 -07:00
compaction.c mm/compaction.c: abort search if isolation fails 2019-04-04 11:56:15 +01:00
debug.c mm/debug.c: fix __dump_page when mapping->host is not set 2019-03-29 10:01:37 -07:00
debug_page_ref.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dmapool.c docs/core-api/mm: fix return value descriptions in mm/ 2019-03-05 21:07:20 -08:00
early_ioremap.c mm/early_ioremap: Fix boot hang with earlyprintk=efi,keep 2017-12-11 14:54:44 +01:00
fadvise.c vfs: implement readahead(2) using POSIX_FADV_WILLNEED 2018-08-30 20:01:32 +02:00
failslab.c mm: no need to check return value of debugfs_create functions 2019-03-05 21:07:17 -08:00
filemap.c mm: page cache: store only head pages in i_pages 2019-05-14 09:47:45 -07:00
frame_vector.c mm/frame_vector.c: release a semaphore in 'get_vaddr_frames()' 2017-12-14 16:00:48 -08:00
frontswap.c mm: use octal not symbolic permissions 2018-06-15 07:55:25 +09:00
gup.c Merge branch 'page-refs' (page ref overflow) 2019-04-14 15:09:40 -07:00
gup_benchmark.c mm: no need to check return value of debugfs_create functions 2019-03-05 21:07:17 -08:00
highmem.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
hmm.c mm/hmm: convert to use vm_fault_t 2019-03-12 10:04:00 -07:00
huge_memory.c mm: page cache: store only head pages in i_pages 2019-05-14 09:47:45 -07:00
hugetlb.c mm/hugetlb.c: don't put_page in lock of hugetlb_lock 2019-05-14 09:47:44 -07:00
hugetlb_cgroup.c mm: rename page_counter's count/limit into usage/max 2018-06-07 17:34:35 -07:00
hwpoison-inject.c mm/memory_failure: Remove unused trapno from memory_failure 2018-01-23 12:17:42 -06:00
init-mm.c mm: Allocate the mm_cpumask (mm->cpu_bitmap[]) dynamically based on nr_cpu_ids 2018-07-17 09:35:30 +02:00
internal.h mm, compaction: capture a page under direct compaction 2019-03-05 21:07:17 -08:00
interval_tree.c mm/interval_tree.c: use vma_pages() helper 2018-01-31 17:18:37 -08:00
Kconfig ksm: replace jhash2 with xxhash 2018-12-28 12:11:46 -08:00
Kconfig.debug mm/page_owner: move config option to mm/Kconfig.debug 2019-03-05 21:07:18 -08:00
khugepaged.c mm: page cache: store only head pages in i_pages 2019-05-14 09:47:45 -07:00
kmemleak-test.c
kmemleak.c Merge branch 'core-stacktrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-05-06 13:11:48 -07:00
ksm.c mm: ksm: do not block on page lock when searching stable tree 2019-03-05 21:07:19 -08:00
list_lru.c numa: make "nr_node_ids" unsigned int 2019-03-05 21:07:19 -08:00
maccess.c Revert "x86/fault: BUG() when uaccess helpers fault on kernel addresses" 2019-02-25 09:10:51 -08:00
madvise.c asm-generic/tlb, arch: Provide CONFIG_HAVE_MMU_GATHER_PAGE_SIZE 2019-04-03 10:32:40 +02:00
Makefile mm: remove nobootmem 2018-10-31 08:54:16 -07:00
memblock.c Printk changes for 5.2 2019-05-07 09:18:12 -07:00
memcontrol.c mm: writeback: use exact memcg dirty counts 2019-04-05 16:02:31 -10:00
memfd.c mm: page cache: store only head pages in i_pages 2019-05-14 09:47:45 -07:00
memory-failure.c mm: hwpoison: fix thp split handing in soft_offline_in_use_page() 2019-03-05 21:07:13 -08:00
memory.c Printk changes for 5.2 2019-05-07 09:18:12 -07:00
memory_hotplug.c mm/memory_hotplug.c: drop memory device reference after find_memory_block() 2019-04-26 09:18:04 -07:00
mempolicy.c mm: mempolicy: make mbind() return -EIO when MPOL_MF_STRICT is specified 2019-03-29 10:01:37 -07:00
mempool.c docs/core-api/mm: fix return value descriptions in mm/ 2019-03-05 21:07:20 -08:00
memtest.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
migrate.c mm: page cache: store only head pages in i_pages 2019-05-14 09:47:45 -07:00
mincore.c Revert "Change mincore() to count "mapped" pages rather than "cached" pages" 2019-01-24 09:04:37 +13:00
mlock.c mm: remove zone_lru_lock() function, access ->lru_lock directly 2019-03-05 21:07:21 -08:00
mm_init.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00
mmap.c coredump: fix race condition between mmget_not_zero()/get_task_mm() and core dumping 2019-04-19 09:46:05 -07:00
mmu_context.c
mmu_gather.c asm-generic/tlb: Remove tlb_table_flush() 2019-04-03 10:33:02 +02:00
mmu_notifier.c mm/mmu_notifier: use structure for invalidate_range_start/end calls v2 2018-12-28 12:11:50 -08:00
mmzone.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mprotect.c mm: update ptep_modify_prot_commit to take old pte value as arg 2019-03-05 21:07:18 -08:00
mremap.c mm,mremap: bail out earlier in mremap_to under map pressure 2019-03-05 21:07:21 -08:00
msync.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nommu.c mm/gup: cache dev_pagemap while pinning pages 2018-10-26 16:38:15 -07:00
oom_kill.c mm,oom: don't kill global init via memory.oom.group 2019-03-05 21:07:19 -08:00
page-writeback.c docs/core-api/mm: fix return value descriptions in mm/ 2019-03-05 21:07:20 -08:00
page_alloc.c mm, page_alloc: disallow __GFP_COMP in alloc_pages_exact() 2019-05-14 09:47:45 -07:00
page_counter.c memcg: introduce memory.min 2018-06-07 17:34:36 -07:00
page_ext.c memblock: drop memblock_alloc_*_nopanic() variants 2019-03-12 10:04:02 -07:00
page_idle.c mm: remove zone_lru_lock() function, access ->lru_lock directly 2019-03-05 21:07:21 -08:00
page_io.c mm/page_io.c: fix polled swap page in 2019-01-04 13:13:48 -08:00
page_isolation.c mm/page_isolation.c: fix a wrong flag in set_migratetype_isolate() 2019-03-29 10:01:37 -07:00
page_owner.c mm/page_owner: Simplify stack trace handling 2019-04-29 12:37:50 +02:00
page_poison.c page_poison: play nicely with KASAN 2019-03-05 21:07:13 -08:00
page_vma_mapped.c mm/rmap: map_pte() was not handling private ZONE_DEVICE page properly 2018-10-31 08:54:11 -07:00
pagewalk.c mm: kernel-doc: add missing parameter descriptions 2018-04-05 21:36:27 -07:00
percpu-internal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
percpu-km.c percpu: km: no need to consider pcpu_group_offsets[0] 2019-02-26 13:47:58 -08:00
percpu-stats.c treewide: Use array_size() in vmalloc() 2018-06-12 16:19:22 -07:00
percpu-vm.c percpu: allow select gfp to be passed to underlying allocators 2018-02-18 05:33:01 -08:00
percpu.c percpu: stop printing kernel addresses 2019-03-18 10:36:36 -07:00
pgtable-generic.c x86/mm: Page size aware flush_tlb_mm_range() 2018-10-09 16:51:11 +02:00
process_vm_access.c mm: docs: add blank lines to silence sphinx "Unexpected indentation" errors 2018-02-06 18:32:48 -08:00
quicklist.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
readahead.c docs/core-api/mm: fix return value descriptions in mm/ 2019-03-05 21:07:20 -08:00
rmap.c mm: remove zone_lru_lock() function, access ->lru_lock directly 2019-03-05 21:07:21 -08:00
rodata_test.c
shmem.c mm: page cache: store only head pages in i_pages 2019-05-14 09:47:45 -07:00
slab.c mm/slab.c: fix an infinite loop in leaks_show() 2019-05-14 09:47:45 -07:00
slab.h mm: add support for kmem caches in DMA32 zone 2019-03-29 10:01:37 -07:00
slab_common.c mm: add support for kmem caches in DMA32 zone 2019-03-29 10:01:37 -07:00
slob.c slob: use slab_list instead of lru 2019-05-14 09:47:44 -07:00
slub.c mm/slub.c: update the comment about slab frozen 2019-05-14 09:47:45 -07:00
sparse-vmemmap.c mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
sparse.c mm/hotplug: fix offline undo_isolate_page_range() 2019-03-29 10:01:37 -07:00
swap.c mm: remove zone_lru_lock() function, access ->lru_lock directly 2019-03-05 21:07:21 -08:00
swap_cgroup.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
swap_slots.c mm, swap, get_swap_pages: use entry_size instead of cluster in parameter 2018-08-22 10:52:44 -07:00
swap_state.c mm: page cache: store only head pages in i_pages 2019-05-14 09:47:45 -07:00
swapfile.c mm: swapoff: shmem_unuse() stop eviction without igrab() 2019-04-19 09:46:04 -07:00
truncate.c docs/core-api/mm: fix return value descriptions in mm/ 2019-03-05 21:07:20 -08:00
usercopy.c mm/usercopy.c: no check page span for stack objects 2019-01-08 17:15:11 -08:00
userfaultfd.c hugetlbfs: revert "use i_mmap_rwsem for more pmd sharing synchronization" 2019-01-08 17:15:11 -08:00
util.c mm/util.c: fix strndup_user() comment 2019-04-05 16:02:31 -10:00
vmacache.c mm: get rid of vmacache_flush_all() entirely 2018-09-13 15:18:04 -10:00
vmalloc.c mm/vmalloc: Add flag for freeing of special permsissions 2019-04-30 12:37:58 +02:00
vmpressure.c mm/vmpressure.c: convert to use match_string() helper 2018-06-07 17:34:36 -07:00
vmscan.c Printk changes for 5.2 2019-05-07 09:18:12 -07:00
vmstat.c mm/vmstat.c: fix /proc/vmstat format for CONFIG_DEBUG_TLBFLUSH=y CONFIG_SMP=n 2019-04-19 09:46:04 -07:00
workingset.c mm/workingset: remove unused @mapping argument in workingset_eviction() 2019-03-05 21:07:21 -08:00
z3fold.c z3fold: fix possible reclaim races 2018-11-18 10:15:09 -08:00
zbud.c mm: docs: fix parameter names mismatch 2018-02-06 18:32:48 -08:00
zpool.c mm/zpool.c: zpool_evictable: fix mismatch in parameter name and kernel-doc 2018-02-21 15:35:43 -08:00
zsmalloc.c mm/zsmalloc.c: fix fall-through annotation 2018-10-26 16:26:35 -07:00
zswap.c mm: convert totalram_pages and totalhigh_pages variables to atomic 2018-12-28 12:11:47 -08:00