code.ossystems Code Review - openembedded-core.git/blob

   1 From 87b2affc3eb06f3fb2d0923f18af37713eb6814b Mon Sep 17 00:00:00 2001
   2 From: Michael Jeanson <mjeanson@efficios.com>
   3 Date: Mon, 31 Aug 2020 14:16:01 -0400
   4 Subject: [PATCH 08/10] fix: writeback: Fix sync livelock due to b_dirty_time
   5  processing (v5.9)
   6
   7 See upstream commit:
   8
   9   commit f9cae926f35e8230330f28c7b743ad088611a8de
  10   Author: Jan Kara <jack@suse.cz>
  11   Date:   Fri May 29 16:08:58 2020 +0200
  12
  13     writeback: Fix sync livelock due to b_dirty_time processing
  14
  15     When we are processing writeback for sync(2), move_expired_inodes()
  16     didn't set any inode expiry value (older_than_this). This can result in
  17     writeback never completing if there's steady stream of inodes added to
  18     b_dirty_time list as writeback rechecks dirty lists after each writeback
  19     round whether there's more work to be done. Fix the problem by using
  20     sync(2) start time is inode expiry value when processing b_dirty_time
  21     list similarly as for ordinarily dirtied inodes. This requires some
  22     refactoring of older_than_this handling which simplifies the code
  23     noticeably as a bonus.
  24
  25 Upstream-Status: Backport
  26
  27 Change-Id: I8b894b13ccc14d9b8983ee4c2810a927c319560b
  28 Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
  29 Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  30 ---
  31  .../events/lttng-module/writeback.h           | 39 ++++++++++++-------
  32  1 file changed, 26 insertions(+), 13 deletions(-)
  33
  34 diff --git a/instrumentation/events/lttng-module/writeback.h b/instrumentation/events/lttng-module/writeback.h
  35 index ece67ad..e9018dd 100644
  36 --- a/instrumentation/events/lttng-module/writeback.h
  37 +++ b/instrumentation/events/lttng-module/writeback.h
  38 @@ -384,34 +384,48 @@ LTTNG_TRACEPOINT_EVENT_WBC_INSTANCE(wbc_balance_dirty_wait, writeback_wbc_balanc
  39  #endif
  40  LTTNG_TRACEPOINT_EVENT_WBC_INSTANCE(wbc_writepage, writeback_wbc_writepage)
  41
  42 -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,1,0))
  43 +#if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,9,0))
  44 +LTTNG_TRACEPOINT_EVENT(writeback_queue_io,
  45 +       TP_PROTO(struct bdi_writeback *wb,
  46 +                struct wb_writeback_work *work,
  47 +                unsigned long dirtied_before,
  48 +                int moved),
  49 +       TP_ARGS(wb, work, dirtied_before, moved),
  50 +       TP_FIELDS(
  51 +               ctf_array_text(char, name, dev_name(wb->bdi->dev), 32)
  52 +               ctf_integer(unsigned long, older, dirtied_before)
  53 +               ctf_integer(int, moved, moved)
  54 +       )
  55 +)
  56 +#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,0))
  57  LTTNG_TRACEPOINT_EVENT(writeback_queue_io,
  58         TP_PROTO(struct bdi_writeback *wb,
  59 -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,0))
  60                  struct wb_writeback_work *work,
  61 -#else
  62 -                unsigned long *older_than_this,
  63 -#endif
  64                  int moved),
  65 -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,0))
  66         TP_ARGS(wb, work, moved),
  67 -#else
  68 +       TP_FIELDS(
  69 +               ctf_array_text(char, name, dev_name(wb->bdi->dev), 32)
  70 +               ctf_integer(int, moved, moved)
  71 +       )
  72 +)
  73 +#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(3,1,0))
  74 +LTTNG_TRACEPOINT_EVENT(writeback_queue_io,
  75 +       TP_PROTO(struct bdi_writeback *wb,
  76 +                unsigned long *older_than_this,
  77 +                int moved),
  78         TP_ARGS(wb, older_than_this, moved),
  79 -#endif
  80         TP_FIELDS(
  81                 ctf_array_text(char, name, dev_name(wb->bdi->dev), 32)
  82 -#if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,0))
  83 -#else
  84                 ctf_integer(unsigned long, older,
  85                         older_than_this ? *older_than_this : 0)
  86                 ctf_integer(long, age,
  87                         older_than_this ?
  88                                 (jiffies - *older_than_this) * 1000 / HZ
  89                                 : -1)
  90 -#endif
  91                 ctf_integer(int, moved, moved)
  92         )
  93  )
  94 +#endif
  95
  96  #if (LINUX_VERSION_CODE >= KERNEL_VERSION(5,8,0))
  97  LTTNG_TRACEPOINT_EVENT_MAP(global_dirty_state,
  98 @@ -460,7 +474,7 @@ LTTNG_TRACEPOINT_EVENT_MAP(global_dirty_state,
  99                 ctf_integer(unsigned long, dirty_limit, global_dirty_limit)
 100         )
 101  )
 102 -#else
 103 +#elif (LINUX_VERSION_CODE >= KERNEL_VERSION(3,1,0))
 104  LTTNG_TRACEPOINT_EVENT_MAP(global_dirty_state,
 105
 106         writeback_global_dirty_state,
 107 @@ -485,7 +499,6 @@ LTTNG_TRACEPOINT_EVENT_MAP(global_dirty_state,
 108         )
 109  )
 110  #endif
 111 -#endif
 112
 113  #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3,2,0))
 114
 115 --
 116 2.19.1
 117