On 02/29/2016 02:26 PM, Michal Hocko wrote:
From: Michal Hocko <[email protected]>
This is the first step in making mmap_sem write holders killable. It
s/holders/waiters/?
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 <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Johannes Weiner <[email protected]>
Signed-off-by: Michal Hocko <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
