This patch moves the _put logic to be processed in a separate thread that holds no other locks to prevent deadlocks like below from happening > there are 6 processes looping to while trying to down_write > cinode->lock_sem, 5 of them from _cifsFileInfo_put, and one from > cifs_new_fileinfo > > and there are 5 other processes which are blocked, several of them > waiting on either PG_writeback or PG_locked (which are both set), all > for the same page of the file > > 2 inode_lock() (inode->i_rwsem) for the file > 1 wait_on_page_writeback() for the page > 1 down_read(inode->i_rwsem) for the inode of the directory > 1 inode_lock()(inode->i_rwsem) for the inode of the directory > 1 __lock_page > > > so processes are blocked waiting on: > page flags PG_locked and PG_writeback for one specific page > inode->i_rwsem for the directory > inode->i_rwsem for the file > cifsInodeInflock_sem > > > > here are the more gory details (let me know if I need to provide > anything more/better): > > [0 00:48:22.765] [UN] PID: 8863 TASK: ffff8c691547c5c0 CPU: 3 > COMMAND: "reopen_file" > #0 [ffff9965007e3ba8] __schedule at ffffffff9b6e6095 > #1 [ffff9965007e3c38] schedule at ffffffff9b6e64df > #2 [ffff9965007e3c48] rwsem_down_write_slowpath at ffffffff9af283d7 > #3 [ffff9965007e3cb8] legitimize_path at ffffffff9b0f975d > #4 [ffff9965007e3d08] path_openat at ffffffff9b0fe55d > #5 [ffff9965007e3dd8] do_filp_open at ffffffff9b100a33 > #6 [ffff9965007e3ee0] do_sys_open at ffffffff9b0eb2d6 > #7 [ffff9965007e3f38] do_syscall_64 at ffffffff9ae04315 > * (I think legitimize_path is bogus) > > in path_openat > } else { > const char *s = path_init(nd, flags); > while (!(error = link_path_walk(s, nd)) && > (error = do_last(nd, file, op)) > 0) { <<<< > > do_last: > if (open_flag & O_CREAT) > inode_lock(dir->d_inode); <<<< > else > so it's trying to take inode->i_rwsem for the directory > > DENTRY INODE SUPERBLK TYPE PATH > ffff8c68bb8e79c0 ffff8c691158ef20 ffff8c6915bf9000 DIR /mnt/vm1_smb/ > inode.i_rwsem is ffff8c691158efc0 > > <struct rw_semaphore 0xffff8c691158efc0>: > owner: <struct task_struct 0xffff8c6914275d00> (UN - 8856 - > reopen_file), counter: 0x0000000000000003 > waitlist: 2 > 0xffff9965007e3c90 8863 reopen_file UN 0 1:29:22.926 > RWSEM_WAITING_FOR_WRITE > 0xffff996500393e00 9802 ls UN 0 1:17:26.700 > RWSEM_WAITING_FOR_READ > > > the owner of the inode.i_rwsem of the directory is: > > [0 00:00:00.109] [UN] PID: 8856 TASK: ffff8c6914275d00 CPU: 3 > COMMAND: "reopen_file" > #0 [ffff99650065b828] __schedule at ffffffff9b6e6095 > #1 [ffff99650065b8b8] schedule at ffffffff9b6e64df > #2 [ffff99650065b8c8] schedule_timeout at ffffffff9b6e9f89 > #3 [ffff99650065b940] msleep at ffffffff9af573a9 > #4 [ffff99650065b948] _cifsFileInfo_put.cold.63 at ffffffffc0a42dd6 [cifs] > #5 [ffff99650065ba38] cifs_writepage_locked at ffffffffc0a0b8f3 [cifs] > #6 [ffff99650065bab0] cifs_launder_page at ffffffffc0a0bb72 [cifs] > #7 [ffff99650065bb30] invalidate_inode_pages2_range at ffffffff9b04d4bd > #8 [ffff99650065bcb8] cifs_invalidate_mapping at ffffffffc0a11339 [cifs] > #9 [ffff99650065bcd0] cifs_revalidate_mapping at ffffffffc0a1139a [cifs] > #10 [ffff99650065bcf0] cifs_d_revalidate at ffffffffc0a014f6 [cifs] > #11 [ffff99650065bd08] path_openat at ffffffff9b0fe7f7 > #12 [ffff99650065bdd8] do_filp_open at ffffffff9b100a33 > #13 [ffff99650065bee0] do_sys_open at ffffffff9b0eb2d6 > #14 [ffff99650065bf38] do_syscall_64 at ffffffff9ae04315 > > cifs_launder_page is for page 0xffffd1e2c07d2480 > > crash> page.index,mapping,flags 0xffffd1e2c07d2480 > index = 0x8 > mapping = 0xffff8c68f3cd0db0 > flags = 0xfffffc0008095 > > PAGE-FLAG BIT VALUE > PG_locked 0 0000001 > PG_uptodate 2 0000004 > PG_lru 4 0000010 > PG_waiters 7 0000080 > PG_writeback 15 0008000 > > > inode is ffff8c68f3cd0c40 > inode.i_rwsem is ffff8c68f3cd0ce0 > DENTRY INODE SUPERBLK TYPE PATH > ffff8c68a1f1b480 ffff8c68f3cd0c40 ffff8c6915bf9000 REG > /mnt/vm1_smb/testfile.8853 > > > this process holds the inode->i_rwsem for the parent directory, is > laundering a page attached to the inode of the file it's opening, and in > _cifsFileInfo_put is trying to down_write the cifsInodeInflock_sem > for the file itself. > > > <struct rw_semaphore 0xffff8c68f3cd0ce0>: > owner: <struct task_struct 0xffff8c6914272e80> (UN - 8854 - > reopen_file), counter: 0x0000000000000003 > waitlist: 1 > 0xffff9965005dfd80 8855 reopen_file UN 0 1:29:22.912 > RWSEM_WAITING_FOR_WRITE > > this is the inode.i_rwsem for the file > > the owner: > > [0 00:48:22.739] [UN] PID: 8854 TASK: ffff8c6914272e80 CPU: 2 > COMMAND: "reopen_file" > #0 [ffff99650054fb38] __schedule at ffffffff9b6e6095 > #1 [ffff99650054fbc8] schedule at ffffffff9b6e64df > #2 [ffff99650054fbd8] io_schedule at ffffffff9b6e68e2 > #3 [ffff99650054fbe8] __lock_page at ffffffff9b03c56f > #4 [ffff99650054fc80] pagecache_get_page at ffffffff9b03dcdf > #5 [ffff99650054fcc0] grab_cache_page_write_begin at ffffffff9b03ef4c > #6 [ffff99650054fcd0] cifs_write_begin at ffffffffc0a064ec [cifs] > #7 [ffff99650054fd30] generic_perform_write at ffffffff9b03bba4 > #8 [ffff99650054fda8] __generic_file_write_iter at ffffffff9b04060a > #9 [ffff99650054fdf0] cifs_strict_writev.cold.70 at ffffffffc0a4469b [cifs] > #10 [ffff99650054fe48] new_sync_write at ffffffff9b0ec1dd > #11 [ffff99650054fed0] vfs_write at ffffffff9b0eed35 > #12 [ffff99650054ff00] ksys_write at ffffffff9b0eefd9 > #13 [ffff99650054ff38] do_syscall_64 at ffffffff9ae04315 > > the process holds the inode->i_rwsem for the file to which it's writing, > and is trying to __lock_page for the same page as in the other processes > > > the other tasks: > [0 00:00:00.028] [UN] PID: 8859 TASK: ffff8c6915479740 CPU: 2 > COMMAND: "reopen_file" > #0 [ffff9965007b39d8] __schedule at ffffffff9b6e6095 > #1 [ffff9965007b3a68] schedule at ffffffff9b6e64df > #2 [ffff9965007b3a78] schedule_timeout at ffffffff9b6e9f89 > #3 [ffff9965007b3af0] msleep at ffffffff9af573a9 > #4 [ffff9965007b3af8] cifs_new_fileinfo.cold.61 at ffffffffc0a42a07 [cifs] > #5 [ffff9965007b3b78] cifs_open at ffffffffc0a0709d [cifs] > #6 [ffff9965007b3cd8] do_dentry_open at ffffffff9b0e9b7a > #7 [ffff9965007b3d08] path_openat at ffffffff9b0fe34f > #8 [ffff9965007b3dd8] do_filp_open at ffffffff9b100a33 > #9 [ffff9965007b3ee0] do_sys_open at ffffffff9b0eb2d6 > #10 [ffff9965007b3f38] do_syscall_64 at ffffffff9ae04315 > > this is opening the file, and is trying to down_write cinode->lock_sem > > > [0 00:00:00.041] [UN] PID: 8860 TASK: ffff8c691547ae80 CPU: 2 > COMMAND: "reopen_file" > [0 00:00:00.057] [UN] PID: 8861 TASK: ffff8c6915478000 CPU: 3 > COMMAND: "reopen_file" > [0 00:00:00.059] [UN] PID: 8858 TASK: ffff8c6914271740 CPU: 2 > COMMAND: "reopen_file" > [0 00:00:00.109] [UN] PID: 8862 TASK: ffff8c691547dd00 CPU: 6 > COMMAND: "reopen_file" > #0 [ffff9965007c3c78] __schedule at ffffffff9b6e6095 > #1 [ffff9965007c3d08] schedule at ffffffff9b6e64df > #2 [ffff9965007c3d18] schedule_timeout at ffffffff9b6e9f89 > #3 [ffff9965007c3d90] msleep at ffffffff9af573a9 > #4 [ffff9965007c3d98] _cifsFileInfo_put.cold.63 at ffffffffc0a42dd6 [cifs] > #5 [ffff9965007c3e88] cifs_close at ffffffffc0a07aaf [cifs] > #6 [ffff9965007c3ea0] __fput at ffffffff9b0efa6e > #7 [ffff9965007c3ee8] task_work_run at ffffffff9aef1614 > #8 [ffff9965007c3f20] exit_to_usermode_loop at ffffffff9ae03d6f > #9 [ffff9965007c3f38] do_syscall_64 at ffffffff9ae0444c > > closing the file, and trying to down_write cifsi->lock_sem > > > [0 00:48:22.839] [UN] PID: 8857 TASK: ffff8c6914270000 CPU: 7 > COMMAND: "reopen_file" > #0 [ffff9965006a7cc8] __schedule at ffffffff9b6e6095 > #1 [ffff9965006a7d58] schedule at ffffffff9b6e64df > #2 [ffff9965006a7d68] io_schedule at ffffffff9b6e68e2 > #3 [ffff9965006a7d78] wait_on_page_bit at ffffffff9b03cac6 > #4 [ffff9965006a7e10] __filemap_fdatawait_range at ffffffff9b03b028 > #5 [ffff9965006a7ed8] filemap_write_and_wait at ffffffff9b040165 > #6 [ffff9965006a7ef0] cifs_flush at ffffffffc0a0c2fa [cifs] > #7 [ffff9965006a7f10] filp_close at ffffffff9b0e93f1 > #8 [ffff9965006a7f30] __x64_sys_close at ffffffff9b0e9a0e > #9 [ffff9965006a7f38] do_syscall_64 at ffffffff9ae04315 > > in __filemap_fdatawait_range > wait_on_page_writeback(page); > for the same page of the file > > > > [0 00:48:22.718] [UN] PID: 8855 TASK: ffff8c69142745c0 CPU: 7 > COMMAND: "reopen_file" > #0 [ffff9965005dfc98] __schedule at ffffffff9b6e6095 > #1 [ffff9965005dfd28] schedule at ffffffff9b6e64df > #2 [ffff9965005dfd38] rwsem_down_write_slowpath at ffffffff9af283d7 > #3 [ffff9965005dfdf0] cifs_strict_writev at ffffffffc0a0c40a [cifs] > #4 [ffff9965005dfe48] new_sync_write at ffffffff9b0ec1dd > #5 [ffff9965005dfed0] vfs_write at ffffffff9b0eed35 > #6 [ffff9965005dff00] ksys_write at ffffffff9b0eefd9 > #7 [ffff9965005dff38] do_syscall_64 at ffffffff9ae04315 > > inode_lock(inode); > > > and one 'ls' later on, to see whether the rest of the mount is available > (the test file is in the root, so we get blocked up on the directory > ->i_rwsem), so the entire mount is unavailable > > [0 00:36:26.473] [UN] PID: 9802 TASK: ffff8c691436ae80 CPU: 4 > COMMAND: "ls" > #0 [ffff996500393d28] __schedule at ffffffff9b6e6095 > #1 [ffff996500393db8] schedule at ffffffff9b6e64df > #2 [ffff996500393dc8] rwsem_down_read_slowpath at ffffffff9b6e9421 > #3 [ffff996500393e78] down_read_killable at ffffffff9b6e95e2 > #4 [ffff996500393e88] iterate_dir at ffffffff9b103c56 > #5 [ffff996500393ec8] ksys_getdents64 at ffffffff9b104b0c > #6 [ffff996500393f30] __x64_sys_getdents64 at ffffffff9b104bb6 > #7 [ffff996500393f38] do_syscall_64 at ffffffff9ae04315 > > in iterate_dir: > if (shared) > res = down_read_killable(&inode->i_rwsem); <<<< > else > res = down_write_killable(&inode->i_rwsem); > Reported-by: Frank Sorenson <sorenson@xxxxxxxxxx>: Signed-off-by: Ronnie Sahlberg <lsahlber@xxxxxxxxxx> --- fs/cifs/cifsfs.c | 13 ++++++++- fs/cifs/cifsglob.h | 1 + fs/cifs/file.c | 79 +++++++++++++++++++++++++++++++++++++----------------- 3 files changed, 68 insertions(+), 25 deletions(-) diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index e4e3b573d20c..f8e201c45ccb 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -119,6 +119,7 @@ extern mempool_t *cifs_mid_poolp; struct workqueue_struct *cifsiod_wq; struct workqueue_struct *decrypt_wq; +struct workqueue_struct *fileinfo_put_wq; struct workqueue_struct *cifsoplockd_wq; __u32 cifs_lock_secret; @@ -1557,11 +1558,18 @@ init_cifs(void) goto out_destroy_cifsiod_wq; } + fileinfo_put_wq = alloc_workqueue("cifsfileinfoput", + WQ_UNBOUND|WQ_FREEZABLE|WQ_MEM_RECLAIM, 0); + if (!fileinfo_put_wq) { + rc = -ENOMEM; + goto out_destroy_decrypt_wq; + } + cifsoplockd_wq = alloc_workqueue("cifsoplockd", WQ_FREEZABLE|WQ_MEM_RECLAIM, 0); if (!cifsoplockd_wq) { rc = -ENOMEM; - goto out_destroy_decrypt_wq; + goto out_destroy_fileinfo_put_wq; } rc = cifs_fscache_register(); @@ -1627,6 +1635,8 @@ init_cifs(void) cifs_fscache_unregister(); out_destroy_cifsoplockd_wq: destroy_workqueue(cifsoplockd_wq); +out_destroy_fileinfo_put_wq: + destroy_workqueue(fileinfo_put_wq); out_destroy_decrypt_wq: destroy_workqueue(decrypt_wq); out_destroy_cifsiod_wq: @@ -1656,6 +1666,7 @@ exit_cifs(void) cifs_fscache_unregister(); destroy_workqueue(cifsoplockd_wq); destroy_workqueue(decrypt_wq); + destroy_workqueue(fileinfo_put_wq); destroy_workqueue(cifsiod_wq); cifs_proc_clean(); } diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index 50dfd9049370..8361e30adcd9 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1902,6 +1902,7 @@ void cifs_queue_oplock_break(struct cifsFileInfo *cfile); extern const struct slow_work_ops cifs_oplock_break_ops; extern struct workqueue_struct *cifsiod_wq; extern struct workqueue_struct *decrypt_wq; +extern struct workqueue_struct *fileinfo_put_wq; extern struct workqueue_struct *cifsoplockd_wq; extern __u32 cifs_lock_secret; diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 0e0217641de1..e222cf04b325 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -368,30 +368,8 @@ cifsFileInfo_get(struct cifsFileInfo *cifs_file) return cifs_file; } -/** - * cifsFileInfo_put - release a reference of file priv data - * - * Always potentially wait for oplock handler. See _cifsFileInfo_put(). - */ -void cifsFileInfo_put(struct cifsFileInfo *cifs_file) -{ - _cifsFileInfo_put(cifs_file, true); -} - -/** - * _cifsFileInfo_put - release a reference of file priv data - * - * This may involve closing the filehandle @cifs_file out on the - * server. Must be called without holding tcon->open_file_lock and - * cifs_file->file_info_lock. - * - * If @wait_for_oplock_handler is true and we are releasing the last - * reference, wait for any running oplock break handler of the file - * and cancel any pending one. If calling this function from the - * oplock break handler, you need to pass false. - * - */ -void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler) +static void +_cifsFileInfo_put_work(struct cifsFileInfo *cifs_file, bool wait_oplock_handler) { struct inode *inode = d_inode(cifs_file->dentry); struct cifs_tcon *tcon = tlink_tcon(cifs_file->tlink); @@ -480,6 +458,59 @@ void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler) kfree(cifs_file); } +struct cifsFileInfo_w { + struct work_struct put; + struct cifsFileInfo *cifs_file; + bool wait_oplock_handler; +}; + +static void cifsFileInfo_put_work(struct work_struct *work) +{ + struct cifsFileInfo_w *cfiw = container_of(work, + struct cifsFileInfo_w, put); + _cifsFileInfo_put_work(cfiw->cifs_file, cfiw->wait_oplock_handler); + kfree(cfiw); +} + +/** + * cifsFileInfo_put - release a reference of file priv data + * + * Always potentially wait for oplock handler. See _cifsFileInfo_put(). + */ +void cifsFileInfo_put(struct cifsFileInfo *cifs_file) +{ + _cifsFileInfo_put(cifs_file, true); +} + +/** + * _cifsFileInfo_put - release a reference of file priv data + * + * This may involve closing the filehandle @cifs_file out on the + * server. Must be called without holding tcon->open_file_lock and + * cifs_file->file_info_lock. + * + * If @wait_for_oplock_handler is true and we are releasing the last + * reference, wait for any running oplock break handler of the file + * and cancel any pending one. If calling this function from the + * oplock break handler, you need to pass false. + * + */ +void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler) +{ + struct cifsFileInfo_w *work; + + work = kmalloc(sizeof(struct cifsFileInfo_w), GFP_KERNEL); + if (work == NULL) { + _cifsFileInfo_put_work(cifs_file, wait_oplock_handler); + return; + } + + INIT_WORK(&work->put, cifsFileInfo_put_work); + work->cifs_file = cifs_file; + work->wait_oplock_handler = wait_oplock_handler; + queue_work(fileinfo_put_wq, &work->put); +} + int cifs_open(struct inode *inode, struct file *file) { -- 2.13.6