From 7064dd5c36187725e7ccfd837e07678ae435d3f5 Mon Sep 17 00:00:00 2001 From: Filipe Manana Date: Fri, 8 Aug 2014 02:47:05 +0100 Subject: [PATCH] Btrfs: don't monopolize a core when evicting inode If an inode has a very large number of extent maps, we can spend a lot of time freeing them, which triggers a soft lockup warning. Therefore reschedule if we need to when freeing the extent maps while evicting the inode. I could trigger this all the time by running xfstests/generic/299 on a file system with the no-holes feature enabled. That test creates an inode with 11386677 extent maps. $ mkfs.btrfs -f -O no-holes $TEST_DEV $ MKFS_OPTIONS="-O no-holes" ./check generic/299 generic/299 382s ... Message from syslogd@debian-vm3 at Aug 7 10:44:29 ... kernel:[85304.208017] BUG: soft lockup - CPU#0 stuck for 22s! [umount:25330] 384s Ran: generic/299 Passed all 1 tests $ dmesg (...) [86304.300017] BUG: soft lockup - CPU#0 stuck for 23s! [umount:25330] (...) [86304.300036] Call Trace: [86304.300036] [] __slab_free+0x54/0x295 [86304.300036] [] ? free_extent_map+0x5c/0xb0 [btrfs] [86304.300036] [] kmem_cache_free+0x282/0x2a0 [86304.300036] [] free_extent_map+0x5c/0xb0 [btrfs] [86304.300036] [] btrfs_evict_inode+0xd5/0x660 [btrfs] [86304.300036] [] ? __inode_wait_for_writeback+0x6d/0xc0 [86304.300036] [] ? _raw_spin_unlock+0x2b/0x40 [86304.300036] [] evict+0xab/0x180 [86304.300036] [] dispose_list+0x3e/0x60 [86304.300036] [] evict_inodes+0xf4/0x110 [86304.300036] [] generic_shutdown_super+0x53/0x110 [86304.300036] [] kill_anon_super+0x16/0x30 [86304.300036] [] btrfs_kill_super+0x1a/0xa0 [btrfs] [86304.300036] [] deactivate_locked_super+0x59/0x80 [86304.300036] [] deactivate_super+0x4e/0x70 [86304.300036] [] mntput_no_expire+0x174/0x1f0 [86304.300036] [] ? mntput_no_expire+0x17/0x1f0 [86304.300036] [] SyS_umount+0x97/0x100 (...) Signed-off-by: Filipe Manana Reviewed-by: Satoru Takeuchi Tested-by: Satoru Takeuchi Signed-off-by: Chris Mason --- fs/btrfs/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 57c3129ee2a2..2ac260d41ccd 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4674,6 +4674,11 @@ static void evict_inode_truncate_pages(struct inode *inode) clear_bit(EXTENT_FLAG_LOGGING, &em->flags); remove_extent_mapping(map_tree, em); free_extent_map(em); + if (need_resched()) { + write_unlock(&map_tree->lock); + cond_resched(); + write_lock(&map_tree->lock); + } } write_unlock(&map_tree->lock); @@ -4696,6 +4701,7 @@ static void evict_inode_truncate_pages(struct inode *inode) &cached_state, GFP_NOFS); free_extent_state(state); + cond_resched(); spin_lock(&io_tree->lock); } spin_unlock(&io_tree->lock); -- 2.30.2