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David Herrmann 05f65b5c70 shm: wait for pins to be released when sealing 
If we set SEAL_WRITE on a file, we must make sure there cannot be any
ongoing write-operations on the file.  For write() calls, we simply lock
the inode mutex, for mmap() we simply verify there're no writable
mappings.  However, there might be pages pinned by AIO, Direct-IO and
similar operations via GUP.  We must make sure those do not write to the
memfd file after we set SEAL_WRITE.

As there is no way to notify GUP users to drop pages or to wait for them
to be done, we implement the wait ourself: When setting SEAL_WRITE, we
check all pages for their ref-count.  If it's bigger than 1, we know
there's some user of the page.  We then mark the page and wait for up to
150ms for those ref-counts to be dropped.  If the ref-counts are not
dropped in time, we refuse the seal operation.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ryan Lortie <desrt@desrt.ca>
Cc: Lennart Poettering <lennart@poettering.net>
Cc: Daniel Mack <zonque@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2014-08-08 15:57:31 -07:00
..
Kconfig mm/zpool: update zswap to use zpool 2014-08-06 18:01:23 -07:00
Kconfig.debug mm: more intensive memory corruption debugging 2012-01-10 16:30:42 -08:00
Makefile mm/zpool: implement common zpool api to zbud/zsmalloc 2014-08-06 18:01:23 -07:00
backing-dev.c arch: Mass conversion of smp_mb__*() 2014-04-18 14:20:48 +02:00
balloon_compaction.c mm: print more details for bad_page() 2014-01-23 16:36:50 -08:00
bootmem.c mm/bootmem.c: remove unused local `map' 2013-11-13 12:09:09 +09:00
cleancache.c mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE 2014-01-23 16:36:50 -08:00
cma.c mm, CMA: clean-up log message 2014-08-06 18:01:16 -07:00
compaction.c mm, compaction: properly signal and act upon lock and need_sched() contention 2014-06-04 16:54:11 -07:00
debug-pagealloc.c
…
dmapool.c mm/dmapool.c: reuse devres_release() to free resources 2014-06-04 16:54:08 -07:00
early_ioremap.c mm: create generic early_ioremap() support 2014-04-07 16:36:15 -07:00
fadvise.c teach SYSCALL_DEFINE<n> how to deal with long long/unsigned long long 2013-03-03 22:46:22 -05:00
failslab.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
filemap.c mm: memcontrol: rewrite uncharge API 2014-08-08 15:57:17 -07:00
filemap_xip.c seqcount: Add lockdep functionality to seqcount/seqlock structures 2013-11-06 12:40:26 +01:00
fremap.c mm: mark remap_file_pages() syscall as deprecated 2014-06-06 16:08:17 -07:00
frontswap.c swap: change swap_list_head to plist, add swap_avail_head 2014-06-04 16:54:07 -07:00
gup.c mm: describe mmap_sem rules for __lock_page_or_retry() and callers 2014-08-06 18:01:20 -07:00
highmem.c mm/highmem: make kmap cache coloring aware 2014-08-06 18:01:22 -07:00
huge_memory.c mm: memcontrol: rewrite charge API 2014-08-08 15:57:17 -07:00
hugetlb.c mm: fix potential infinite loop in dissolve_free_huge_pages() 2014-08-06 18:01:21 -07:00
hugetlb_cgroup.c cgroup: replace cgroup_add_cftypes() with cgroup_add_legacy_cftypes() 2014-07-15 11:05:09 -04:00
hwpoison-inject.c mm/hwpoison-inject.c: remove unnecessary null test before debugfs_remove_recursive 2014-08-06 18:01:19 -07:00
init-mm.c
…
internal.h mm/internal.h: use nth_page 2014-08-06 18:01:16 -07:00
interval_tree.c mm: add CONFIG_DEBUG_VM_RB build option 2012-10-09 16:22:42 +09:00
iov_iter.c bio_vec-backed iov_iter 2014-05-06 17:39:45 -04:00
kmemcheck.c
…
kmemleak-test.c mm/kmemleak-test.c: use pr_fmt for logging 2014-06-06 16:08:18 -07:00
kmemleak.c mm: introduce kmemleak_update_trace() 2014-06-06 16:08:17 -07:00
ksm.c sched: Remove proliferation of wait_on_bit() action functions 2014-07-16 15:10:39 +02:00
list_lru.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
maccess.c
…
madvise.c mm: update the description for madvise_remove 2014-08-06 18:01:18 -07:00
memblock.c mm/memblock.c: call kmemleak directly from memblock_(alloc|free) 2014-06-06 16:08:17 -07:00
memcontrol.c mm: memcontrol: avoid charge statistics churn during page migration 2014-08-08 15:57:18 -07:00
memory-failure.c hwpoison: fix race with changing page during offlining 2014-08-06 18:01:19 -07:00
memory.c arm64,ia64,ppc,s390,sh,tile,um,x86,mm: remove default gate area 2014-08-08 15:57:27 -07:00
memory_hotplug.c memory-hotplug: add zone_for_memory() for selecting zone for new memory 2014-08-06 18:01:21 -07:00
mempolicy.c Merge branch 'for-3.16-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2014-07-10 11:38:23 -07:00
mempool.c mm/mempool.c: update the kmemleak stack trace for mempool allocations 2014-06-06 16:08:17 -07:00
migrate.c mm: memcontrol: rewrite uncharge API 2014-08-08 15:57:17 -07:00
mincore.c mm + fs: prepare for non-page entries in page cache radix trees 2014-04-03 16:21:00 -07:00
mlock.c mm: describe mmap_sem rules for __lock_page_or_retry() and callers 2014-08-06 18:01:20 -07:00
mm_init.c mm: bring back /sys/kernel/mm 2014-01-27 21:02:39 -08:00
mmap.c mm: allow drivers to prevent new writable mappings 2014-08-08 15:57:31 -07:00
mmu_context.c sched/mm: call finish_arch_post_lock_switch in idle_task_exit and use_mm 2014-02-21 08:50:17 +01:00
mmu_notifier.c mmu_notifier: add call_srcu and sync function for listener to delay call and sync 2014-08-06 18:01:22 -07:00
mmzone.c mm: numa: Change page last {nid,pid} into {cpu,pid} 2013-10-09 14:47:45 +02:00
mprotect.c mm: move mmu notifier call from change_protection to change_pmd_range 2014-04-07 16:35:50 -07:00
mremap.c mm, thp: close race between mremap() and split_huge_page() 2014-05-11 17:55:48 +09:00
msync.c msync: fix incorrect fstart calculation 2014-07-03 09:21:53 -07:00
nobootmem.c mm/memblock.c: call kmemleak directly from memblock_(alloc|free) 2014-06-06 16:08:17 -07:00
nommu.c arm64,ia64,ppc,s390,sh,tile,um,x86,mm: remove default gate area 2014-08-08 15:57:27 -07:00
oom_kill.c mm, oom: remove unnecessary exit_state check 2014-08-06 18:01:21 -07:00
page-writeback.c mm, writeback: prevent race when calculating dirty limits 2014-08-06 18:01:21 -07:00
page_alloc.c mm, thp: restructure thp avoidance of light synchronous migration 2014-08-06 18:01:21 -07:00
page_cgroup.c mm/page_cgroup.c: mark functions as static 2014-04-03 16:21:02 -07:00
page_io.c fix __swap_writepage() compile failure on old gcc versions 2014-06-14 19:30:48 -05:00
page_isolation.c mm: memory-hotplug: enable memory hotplug to handle hugepage 2013-09-11 15:57:48 -07:00
pagewalk.c mm/pagewalk.c: fix walk_page_range() access of wrong PTEs 2013-10-30 14:27:03 -07:00
percpu-km.c
…
percpu-vm.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu.c percpu: Use ALIGN macro instead of hand coding alignment calculation 2014-06-19 11:00:27 -04:00
pgtable-generic.c mm: fix TLB flush race between migration, and change_protection_range 2013-12-18 19:04:51 -08:00
process_vm_access.c start adding the tag to iov_iter 2014-05-06 17:32:49 -04:00
quicklist.c
…
readahead.c mm/readahead.c: remove unused file_ra_state from count_history_pages 2014-08-06 18:01:15 -07:00
rmap.c mm: memcontrol: rewrite uncharge API 2014-08-08 15:57:17 -07:00
shmem.c shm: wait for pins to be released when sealing 2014-08-08 15:57:31 -07:00
slab.c Revert "slab: remove BAD_ALIEN_MAGIC" 2014-08-08 15:57:17 -07:00
slab.h slab: convert last use of __FUNCTION__ to __func__ 2014-08-06 18:01:15 -07:00
slab_common.c mm: move slab related stuff from util.c to slab_common.c 2014-08-06 18:01:15 -07:00
slob.c slab: get_online_mems for kmem_cache_{create,destroy,shrink} 2014-06-04 16:53:59 -07:00
slub.c slub: remove kmemcg id from create_unique_id 2014-08-06 18:01:21 -07:00
sparse-vmemmap.c mm/sparse: use memblock apis for early memory allocations 2014-01-21 16:19:47 -08:00
sparse.c mm: use macros from compiler.h instead of __attribute__((...)) 2014-04-07 16:35:54 -07:00
swap.c mm: memcontrol: use page lists for uncharge batching 2014-08-08 15:57:18 -07:00
swap_state.c mm: allow drivers to prevent new writable mappings 2014-08-08 15:57:31 -07:00
swapfile.c mm: memcontrol: rewrite uncharge API 2014-08-08 15:57:17 -07:00
truncate.c mm: memcontrol: rewrite uncharge API 2014-08-08 15:57:17 -07:00
util.c vm_is_stack: use for_each_thread() rather then buggy while_each_thread() 2014-08-08 15:57:17 -07:00
vmacache.c mm,vmacache: optimize overflow system-wide flushing 2014-06-04 16:53:57 -07:00
vmalloc.c mm/vmalloc.c: clean up map_vm_area third argument 2014-08-06 18:01:19 -07:00
vmpressure.c arm, pm, vmpressure: add missing slab.h includes 2014-02-03 13:24:01 -05:00
vmscan.c mm: memcontrol: use page lists for uncharge batching 2014-08-08 15:57:18 -07:00
vmstat.c mm: vmscan: only update per-cpu thresholds for online CPU 2014-08-06 18:01:20 -07:00
workingset.c mm: keep page cache radix tree nodes in check 2014-04-03 16:21:01 -07:00
zbud.c mm/zpool: zbud/zsmalloc implement zpool 2014-08-06 18:01:23 -07:00
zpool.c mm/zpool: implement common zpool api to zbud/zsmalloc 2014-08-06 18:01:23 -07:00
zsmalloc.c mm/zpool: zbud/zsmalloc implement zpool 2014-08-06 18:01:23 -07:00
zswap.c mm/zswap.c: add __init to zswap_entry_cache_destroy() 2014-08-08 15:57:18 -07:00