spl-patches/0002-deadlock-between-mm_sem-and-tx-assign-in-zfs_write-a.patch

   1 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
   2 From: ilbsmart <wgqimut@gmail.com>
   3 Date: Wed, 17 Oct 2018 02:11:24 +0800
   4 Subject: [PATCH] deadlock between mm_sem and tx assign in zfs_write() and page
   5  fault
   6
   7 The bug time sequence:
   8 1. thread #1, `zfs_write` assign a txg "n".
   9 2. In a same process, thread #2, mmap page fault (which means the
  10    `mm_sem` is hold) occurred, `zfs_dirty_inode` open a txg failed,
  11    and wait previous txg "n" completed.
  12 3. thread #1 call `uiomove` to write, however page fault is occurred
  13    in `uiomove`, which means it need `mm_sem`, but `mm_sem` is hold by
  14    thread #2, so it stuck and can't complete,  then txg "n" will
  15    not complete.
  16
  17 So thread #1 and thread #2 are deadlocked.
  18
  19 Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
  20 Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
  21 Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
  22 Signed-off-by: Grady Wong <grady.w@xtaotech.com>
  23 Closes #7939
  24
  25 (backported from: zfs-upstream 779a6c0bf6df76e0dd92c1ccf81f48512b835bb0)
  26 Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
  27 ---
  28  include/sys/uio.h | 1 +
  29  1 file changed, 1 insertion(+)
  30
  31 diff --git a/include/sys/uio.h b/include/sys/uio.h
  32 index 764beb9..2895690 100644
  33 --- a/include/sys/uio.h
  34 +++ b/include/sys/uio.h
  35 @@ -53,6 +53,7 @@ typedef struct uio {
  36         int             uio_iovcnt;
  37         offset_t        uio_loffset;
  38         uio_seg_t       uio_segflg;
  39 +       boolean_t       uio_fault_disable;
  40         uint16_t        uio_fmode;
  41         uint16_t        uio_extflg;
  42         offset_t        uio_limit;