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    SubjectRe: [PATCH 01/18] mm: Make mmap_sem for write waits killable for mm syscalls
    On Thu 10-03-16 16:47:16, Vlastimil Babka wrote:
    > On 02/29/2016 02:26 PM, Michal Hocko wrote:
    > >From: Michal Hocko <mhocko@suse.com>
    > >
    > >This is the first step in making mmap_sem write holders killable. It
    >
    > s/holders/waiters/?

    right. Fixed

    > >focuses on the trivial ones which are taking the lock early after
    > >entering the syscall and they are not changing state before.
    > >
    > >Therefore it is very easy to change them to use down_write_killable
    > >and immediately return with -EINTR. This will allow the waiter to
    > >pass away without blocking the mmap_sem which might be required to
    > >make a forward progress. E.g. the oom reaper will need the lock for
    > >reading to dismantle the OOM victim address space.
    > >
    > >The only tricky function in this patch is vm_mmap_pgoff which has many
    > >call sites via vm_mmap. To reduce the risk keep vm_mmap with the
    > >original non-killable semantic for now.
    > >
    > >vm_munmap callers do not bother checking the return value so open code
    > >it into the munmap syscall path for now for simplicity.
    > >
    > >Cc: Mel Gorman <mgorman@suse.de>
    > >Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
    > >Cc: Konstantin Khlebnikov <koct9i@gmail.com>
    > >Cc: Hugh Dickins <hughd@google.com>
    > >Cc: Andrea Arcangeli <aarcange@redhat.com>
    > >Cc: David Rientjes <rientjes@google.com>
    > >Cc: Dave Hansen <dave.hansen@linux.intel.com>
    > >Cc: Johannes Weiner <hannes@cmpxchg.org>
    > >Signed-off-by: Michal Hocko <mhocko@suse.com>
    >
    > Acked-by: Vlastimil Babka <vbabka@suse.cz>

    Thanks!
    --
    Michal Hocko
    SUSE Labs

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