| Message ID | 1453716126-7282-1-git-send-email-dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 25 Jan 2016, David Sterba wrote: > This reverts commit 696249132158014d594896df3a81390616069c5c. The > cleaner thread can block freezing when there's a snapshot cleaning in > progress and the other threads get suspended first. From the logs > provided by Martin we're waiting for reading extent pages: > > kernel: PM: Syncing filesystems ... done. > kernel: Freezing user space processes ... (elapsed 0.015 seconds) done. > kernel: Freezing remaining freezable tasks ... > kernel: Freezing of tasks failed after 20.003 seconds (1 tasks refusing to freeze, wq_busy=0): > kernel: btrfs-cleaner D ffff88033dd13bc0 0 152 2 0x00000000 > kernel: ffff88032ebc2e00 ffff88032e750000 ffff88032e74fa50 7fffffffffffffff > kernel: ffffffff814a58df 0000000000000002 ffffea000934d580 ffffffff814a5451 > kernel: 7fffffffffffffff ffffffff814a6e8f 0000000000000000 0000000000000020 > kernel: Call Trace: > kernel: [<ffffffff814a58df>] ? bit_wait+0x2c/0x2c > kernel: [<ffffffff814a5451>] ? schedule+0x6f/0x7c > kernel: [<ffffffff814a6e8f>] ? schedule_timeout+0x2f/0xd8 > kernel: [<ffffffff81076f94>] ? timekeeping_get_ns+0xa/0x2e > kernel: [<ffffffff81077603>] ? ktime_get+0x36/0x44 > kernel: [<ffffffff814a4f6c>] ? io_schedule_timeout+0x94/0xf2 > kernel: [<ffffffff814a4f6c>] ? io_schedule_timeout+0x94/0xf2 > kernel: [<ffffffff814a590b>] ? bit_wait_io+0x2c/0x30 > kernel: [<ffffffff814a5694>] ? __wait_on_bit+0x41/0x73 > kernel: [<ffffffff8109eba8>] ? wait_on_page_bit+0x6d/0x72 > kernel: [<ffffffff8105d718>] ? autoremove_wake_function+0x2a/0x2a > kernel: [<ffffffff811a02d7>] ? read_extent_buffer_pages+0x1bd/0x203 > kernel: [<ffffffff8117d9e9>] ? free_root_pointers+0x4c/0x4c > kernel: [<ffffffff8117e831>] ? btree_read_extent_buffer_pages.constprop.57+0x5a/0xe9 > kernel: [<ffffffff8117f4f3>] ? read_tree_block+0x2d/0x45 > kernel: [<ffffffff8116782a>] ? read_block_for_search.isra.34+0x22a/0x26b > kernel: [<ffffffff811656c3>] ? btrfs_set_path_blocking+0x1e/0x4a > kernel: [<ffffffff8116919b>] ? btrfs_search_slot+0x648/0x736 > kernel: [<ffffffff81170559>] ? btrfs_lookup_extent_info+0xb7/0x2c7 > kernel: [<ffffffff81170ee5>] ? walk_down_proc+0x9c/0x1ae > kernel: [<ffffffff81171c9d>] ? walk_down_tree+0x40/0xa4 > kernel: [<ffffffff8117375f>] ? btrfs_drop_snapshot+0x2da/0x664 > kernel: [<ffffffff8104ff21>] ? finish_task_switch+0x126/0x167 > kernel: [<ffffffff811850f8>] ? btrfs_clean_one_deleted_snapshot+0xa6/0xb0 > kernel: [<ffffffff8117eaba>] ? cleaner_kthread+0x13e/0x17b > kernel: [<ffffffff8117e97c>] ? btrfs_item_end+0x33/0x33 > kernel: [<ffffffff8104d256>] ? kthread+0x95/0x9d > kernel: [<ffffffff8104d1c1>] ? kthread_parkme+0x16/0x16 > kernel: [<ffffffff814a7b5f>] ? ret_from_fork+0x3f/0x70 > kernel: [<ffffffff8104d1c1>] ? kthread_parkme+0x16/0x16 Proper fix should be calling freezable_schedule() instead of schedule() at the end of the main kthread loop. Calling try_to_freeze() on a non-freezable thread doesn't make any sense, so while I agree with the revert for -stable, I don't think the code should be kept as-is.
On Mon, Jan 25, 2016 at 11:02:06AM +0100, David Sterba wrote: > This reverts commit 696249132158014d594896df3a81390616069c5c. The > cleaner thread can block freezing when there's a snapshot cleaning in > progress and the other threads get suspended first. From the logs > provided by Martin we're waiting for reading extent pages: Sorry, I specifically looked for this kind of interaction when I took the patch and missed it. I'll revert for rc2. -chris > > kernel: PM: Syncing filesystems ... done. > kernel: Freezing user space processes ... (elapsed 0.015 seconds) done. > kernel: Freezing remaining freezable tasks ... > kernel: Freezing of tasks failed after 20.003 seconds (1 tasks refusing to freeze, wq_busy=0): > kernel: btrfs-cleaner D ffff88033dd13bc0 0 152 2 0x00000000 > kernel: ffff88032ebc2e00 ffff88032e750000 ffff88032e74fa50 7fffffffffffffff > kernel: ffffffff814a58df 0000000000000002 ffffea000934d580 ffffffff814a5451 > kernel: 7fffffffffffffff ffffffff814a6e8f 0000000000000000 0000000000000020 > kernel: Call Trace: > kernel: [<ffffffff814a58df>] ? bit_wait+0x2c/0x2c > kernel: [<ffffffff814a5451>] ? schedule+0x6f/0x7c > kernel: [<ffffffff814a6e8f>] ? schedule_timeout+0x2f/0xd8 > kernel: [<ffffffff81076f94>] ? timekeeping_get_ns+0xa/0x2e > kernel: [<ffffffff81077603>] ? ktime_get+0x36/0x44 > kernel: [<ffffffff814a4f6c>] ? io_schedule_timeout+0x94/0xf2 > kernel: [<ffffffff814a4f6c>] ? io_schedule_timeout+0x94/0xf2 > kernel: [<ffffffff814a590b>] ? bit_wait_io+0x2c/0x30 > kernel: [<ffffffff814a5694>] ? __wait_on_bit+0x41/0x73 > kernel: [<ffffffff8109eba8>] ? wait_on_page_bit+0x6d/0x72 > kernel: [<ffffffff8105d718>] ? autoremove_wake_function+0x2a/0x2a > kernel: [<ffffffff811a02d7>] ? read_extent_buffer_pages+0x1bd/0x203 > kernel: [<ffffffff8117d9e9>] ? free_root_pointers+0x4c/0x4c > kernel: [<ffffffff8117e831>] ? btree_read_extent_buffer_pages.constprop.57+0x5a/0xe9 > kernel: [<ffffffff8117f4f3>] ? read_tree_block+0x2d/0x45 > kernel: [<ffffffff8116782a>] ? read_block_for_search.isra.34+0x22a/0x26b > kernel: [<ffffffff811656c3>] ? btrfs_set_path_blocking+0x1e/0x4a > kernel: [<ffffffff8116919b>] ? btrfs_search_slot+0x648/0x736 > kernel: [<ffffffff81170559>] ? btrfs_lookup_extent_info+0xb7/0x2c7 > kernel: [<ffffffff81170ee5>] ? walk_down_proc+0x9c/0x1ae > kernel: [<ffffffff81171c9d>] ? walk_down_tree+0x40/0xa4 > kernel: [<ffffffff8117375f>] ? btrfs_drop_snapshot+0x2da/0x664 > kernel: [<ffffffff8104ff21>] ? finish_task_switch+0x126/0x167 > kernel: [<ffffffff811850f8>] ? btrfs_clean_one_deleted_snapshot+0xa6/0xb0 > kernel: [<ffffffff8117eaba>] ? cleaner_kthread+0x13e/0x17b > kernel: [<ffffffff8117e97c>] ? btrfs_item_end+0x33/0x33 > kernel: [<ffffffff8104d256>] ? kthread+0x95/0x9d > kernel: [<ffffffff8104d1c1>] ? kthread_parkme+0x16/0x16 > kernel: [<ffffffff814a7b5f>] ? ret_from_fork+0x3f/0x70 > kernel: [<ffffffff8104d1c1>] ? kthread_parkme+0x16/0x16 > > As this affects a released kernel (4.4) we need a minimal fix for > stable kernels. > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=108361 > Reported-by: Martin Ziegler <ziegler@uni-freiburg.de> > CC: stable@vger.kernel.org # 4.4 > CC: Jiri Kosina <jkosina@suse.cz> > Signed-off-by: David Sterba <dsterba@suse.com> > --- > fs/btrfs/disk-io.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index 26ef14152093..404e894c33d9 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -1787,7 +1787,6 @@ static int cleaner_kthread(void *arg) > int again; > struct btrfs_trans_handle *trans; > > - set_freezable(); > do { > again = 0; > > -- > 2.6.3 > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 26ef14152093..404e894c33d9 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1787,7 +1787,6 @@ static int cleaner_kthread(void *arg) int again; struct btrfs_trans_handle *trans; - set_freezable(); do { again = 0;
This reverts commit 696249132158014d594896df3a81390616069c5c. The cleaner thread can block freezing when there's a snapshot cleaning in progress and the other threads get suspended first. From the logs provided by Martin we're waiting for reading extent pages: kernel: PM: Syncing filesystems ... done. kernel: Freezing user space processes ... (elapsed 0.015 seconds) done. kernel: Freezing remaining freezable tasks ... kernel: Freezing of tasks failed after 20.003 seconds (1 tasks refusing to freeze, wq_busy=0): kernel: btrfs-cleaner D ffff88033dd13bc0 0 152 2 0x00000000 kernel: ffff88032ebc2e00 ffff88032e750000 ffff88032e74fa50 7fffffffffffffff kernel: ffffffff814a58df 0000000000000002 ffffea000934d580 ffffffff814a5451 kernel: 7fffffffffffffff ffffffff814a6e8f 0000000000000000 0000000000000020 kernel: Call Trace: kernel: [<ffffffff814a58df>] ? bit_wait+0x2c/0x2c kernel: [<ffffffff814a5451>] ? schedule+0x6f/0x7c kernel: [<ffffffff814a6e8f>] ? schedule_timeout+0x2f/0xd8 kernel: [<ffffffff81076f94>] ? timekeeping_get_ns+0xa/0x2e kernel: [<ffffffff81077603>] ? ktime_get+0x36/0x44 kernel: [<ffffffff814a4f6c>] ? io_schedule_timeout+0x94/0xf2 kernel: [<ffffffff814a4f6c>] ? io_schedule_timeout+0x94/0xf2 kernel: [<ffffffff814a590b>] ? bit_wait_io+0x2c/0x30 kernel: [<ffffffff814a5694>] ? __wait_on_bit+0x41/0x73 kernel: [<ffffffff8109eba8>] ? wait_on_page_bit+0x6d/0x72 kernel: [<ffffffff8105d718>] ? autoremove_wake_function+0x2a/0x2a kernel: [<ffffffff811a02d7>] ? read_extent_buffer_pages+0x1bd/0x203 kernel: [<ffffffff8117d9e9>] ? free_root_pointers+0x4c/0x4c kernel: [<ffffffff8117e831>] ? btree_read_extent_buffer_pages.constprop.57+0x5a/0xe9 kernel: [<ffffffff8117f4f3>] ? read_tree_block+0x2d/0x45 kernel: [<ffffffff8116782a>] ? read_block_for_search.isra.34+0x22a/0x26b kernel: [<ffffffff811656c3>] ? btrfs_set_path_blocking+0x1e/0x4a kernel: [<ffffffff8116919b>] ? btrfs_search_slot+0x648/0x736 kernel: [<ffffffff81170559>] ? btrfs_lookup_extent_info+0xb7/0x2c7 kernel: [<ffffffff81170ee5>] ? walk_down_proc+0x9c/0x1ae kernel: [<ffffffff81171c9d>] ? walk_down_tree+0x40/0xa4 kernel: [<ffffffff8117375f>] ? btrfs_drop_snapshot+0x2da/0x664 kernel: [<ffffffff8104ff21>] ? finish_task_switch+0x126/0x167 kernel: [<ffffffff811850f8>] ? btrfs_clean_one_deleted_snapshot+0xa6/0xb0 kernel: [<ffffffff8117eaba>] ? cleaner_kthread+0x13e/0x17b kernel: [<ffffffff8117e97c>] ? btrfs_item_end+0x33/0x33 kernel: [<ffffffff8104d256>] ? kthread+0x95/0x9d kernel: [<ffffffff8104d1c1>] ? kthread_parkme+0x16/0x16 kernel: [<ffffffff814a7b5f>] ? ret_from_fork+0x3f/0x70 kernel: [<ffffffff8104d1c1>] ? kthread_parkme+0x16/0x16 As this affects a released kernel (4.4) we need a minimal fix for stable kernels. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=108361 Reported-by: Martin Ziegler <ziegler@uni-freiburg.de> CC: stable@vger.kernel.org # 4.4 CC: Jiri Kosina <jkosina@suse.cz> Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/disk-io.c | 1 - 1 file changed, 1 deletion(-)