1. 29 Aug, 2017 1 commit
  2. 28 Aug, 2017 38 commits
  3. 27 Aug, 2017 1 commit
    • Linus Torvalds's avatar
      Avoid page waitqueue race leaving possible page locker waiting · a8b169af
      Linus Torvalds authored
      The "lock_page_killable()" function waits for exclusive access to the
      page lock bit using the WQ_FLAG_EXCLUSIVE bit in the waitqueue entry
      That means that if it gets woken up, other waiters may have been
      That, in turn, means that if it sees the page being unlocked, it *must*
      take that lock and return success, even if a lethal signal is also
      So instead of checking for lethal signals first, we need to check for
      them after we've checked the actual bit that we were waiting for.  Even
      if that might then delay the killing of the process.
      This matches the order of the old "wait_on_bit_lock()" infrastructure
      that the page locking used to use (and is still used in a few other
      Note that if we still return an error after having unsuccessfully tried
      to acquire the page lock, that is ok: that means that some other thread
      was able to get ahead of us and lock the page, and when that other
      thread then unlocks the page, the wakeup event will be repeated.  So any
      other pending waiters will now get properly woken up.
      Fixes: 62906027 ("mm: add PageWaiters indicating tasks are waiting for a page bit")
      Cc: Nick Piggin <npiggin@gmail.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Mel Gorman <mgorman@techsingularity.net>
      Cc: Jan Kara <jack@suse.cz>
      Cc: Davidlohr Bueso <dave@stgolabs.net>
      Cc: Andi Kleen <ak@linux.intel.com>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>