Messages in this thread Patch in this message | | | From | Chao Yu <> | Subject | [PATCH 8/8] f2fs: fix to avoid deadlock between checkpoint and writepages | Date | Tue, 15 Dec 2015 13:36:08 +0800 |
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This patch fixes to move f2fs_balance_fs out of sbi->writepages' coverage to avoid potential ABBA deadlock which was found by lockdep:
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- lock(&sbi->writepages); lock(&sbi->cp_mutex); lock(&sbi->writepages); lock(&sbi->cp_mutex);
*** DEADLOCK ***
stack of CPU0: [<ffffffff810b8dd1>] __lock_acquire+0x1321/0x1770 [<ffffffff810b92d7>] lock_acquire+0xb7/0x130 [<ffffffff817ad082>] mutex_lock_nested+0x52/0x380 [<ffffffffa07b767b>] f2fs_balance_fs+0x8b/0xa0 [f2fs] [<ffffffffa07afb5b>] f2fs_write_data_page+0x33b/0x460 [f2fs] [<ffffffffa07ab79a>] __f2fs_writepage+0x1a/0x50 [f2fs] [<ffffffffa07ac693>] T.1541+0x293/0x560 [f2fs] [<ffffffffa07aca8c>] f2fs_write_data_pages+0x12c/0x230 [f2fs] [<ffffffff8118adb3>] do_writepages+0x23/0x40 [<ffffffff8117c545>] __filemap_fdatawrite_range+0xb5/0xf0 [<ffffffff8117c623>] filemap_write_and_wait_range+0xa3/0xd0 [<ffffffffa079cc20>] f2fs_symlink+0x180/0x300 [f2fs] [<ffffffff81208187>] vfs_symlink+0xb7/0xe0 [<ffffffff8120acc5>] SyS_symlinkat+0xc5/0x100 [<ffffffff81205ad6>] SyS_symlink+0x16/0x20 [<ffffffff817b15d7>] entry_SYSCALL_64_fastpath+0x12/0x6f
stack of CPU1 [<ffffffff810b92d7>] lock_acquire+0xb7/0x130 [<ffffffff817ad082>] mutex_lock_nested+0x52/0x380 [<ffffffffa07aca7e>] f2fs_write_data_pages+0x11e/0x230 [f2fs] [<ffffffff8118adb3>] do_writepages+0x23/0x40 [<ffffffff8117c545>] __filemap_fdatawrite_range+0xb5/0xf0 [<ffffffff8117c9ef>] filemap_fdatawrite+0x1f/0x30 [<ffffffffa07a728d>] sync_dirty_inodes+0x4d/0xd0 [f2fs] [<ffffffffa07a7381>] block_operations+0x71/0x160 [f2fs] [<ffffffffa07a85f8>] write_checkpoint+0xe8/0xbb0 [f2fs] [<ffffffffa07a043f>] f2fs_sync_fs+0x8f/0xf0 [f2fs] [<ffffffffa07b63af>] f2fs_balance_fs_bg+0x6f/0xd0 [f2fs] [<ffffffffa07b1c97>] f2fs_write_node_pages+0x57/0x150 [f2fs] [<ffffffff8118adb3>] do_writepages+0x23/0x40 [<ffffffff8122c9ed>] __writeback_single_inode+0x6d/0x3d0 [<ffffffff8122ec87>] writeback_sb_inodes+0x2c7/0x520 [<ffffffff8122f193>] wb_writeback+0x133/0x330 [<ffffffff8122f478>] wb_do_writeback+0xe8/0x270 [<ffffffff8122f680>] wb_workfn+0x80/0x1f0 [<ffffffff81081a1c>] process_one_work+0x20c/0x5c0 [<ffffffff81083c62>] worker_thread+0x132/0x5f0 [<ffffffff8108918e>] kthread+0xde/0x100 [<ffffffff817b193f>] ret_from_fork+0x3f/0x70
Signed-off-by: Chao Yu <chao2.yu@samsung.com> --- fs/f2fs/data.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 2e97057..985671d 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -506,7 +506,6 @@ static void __allocate_data_blocks(struct inode *inode, loff_t offset, u64 end_offset; while (len) { - f2fs_balance_fs(sbi); f2fs_lock_op(sbi); /* When reading holes, we need its node page */ @@ -1186,7 +1185,7 @@ out: if (err) ClearPageUptodate(page); unlock_page(page); - if (need_balance_fs) + if (need_balance_fs && !test_opt(sbi, DATA_FLUSH)) f2fs_balance_fs(sbi); if (wbc->for_reclaim) { f2fs_submit_merged_bio(sbi, DATA, WRITE); @@ -1617,6 +1616,8 @@ static ssize_t f2fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter, trace_f2fs_direct_IO_enter(inode, offset, count, rw); if (rw == WRITE) { + f2fs_balance_fs(sbi); + if (serialized) mutex_lock(&sbi->writepages); __allocate_data_blocks(inode, offset, count); -- 2.6.3
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