If madvise(2) advice will result in the underlying vma being split and the number of areas mapped by the process will exceed /proc/sys/vm/max_map_count as a result, return ENOMEM instead of EAGAIN. EAGAIN is returned by madvise(2) when a kernel resource, such as slab, is temporarily unavailable. It indicates that userspace should retry the advice in the near future. This is important for advice such as MADV_DONTNEED which is often used by malloc implementations to free memory back to the system: we really do want to free memory back when madvise(2) returns EAGAIN because slab allocations (for vmas, anon_vmas, or mempolicies) cannot be allocated. Encountering /proc/sys/vm/max_map_count is not a temporary failure, however, so return ENOMEM to indicate this is a more serious issue. A followup patch to the man page will specify this behavior. Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701241431120.42507@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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.. | ||
.gitignore | ||
00-INDEX | ||
active_mm.txt | ||
balance | ||
cleancache.txt | ||
frontswap.txt | ||
highmem.txt | ||
hugetlbpage.txt | ||
hwpoison.txt | ||
idle_page_tracking.txt | ||
ksm.txt | ||
numa | ||
numa_memory_policy.txt | ||
overcommit-accounting | ||
page_frags | ||
page_migration | ||
page_owner.txt | ||
pagemap.txt | ||
remap_file_pages.txt | ||
slub.txt | ||
soft-dirty.txt | ||
split_page_table_lock | ||
transhuge.txt | ||
unevictable-lru.txt | ||
userfaultfd.txt | ||
z3fold.txt | ||
zsmalloc.txt | ||
zswap.txt |