From: Ronnie Sahlberg lsahlber@redhat.com
[ Upstream commit 32546a9586aa4565035bb557e191648e022b29e8 ]
This patch moves the final part of the cifsFileInfo_put() logic where we need a write lock on lock_sem to be processed in a separate thread that holds no other locks. This is to prevent deadlocks like the one below:
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 PATHffff8c68bb8e79c0 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@redhat.com Reviewed-by: Pavel Shilovsky pshilov@microsoft.com Signed-off-by: Ronnie Sahlberg lsahlber@redhat.com Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/cifs/cifsfs.c | 13 +++++++- fs/cifs/cifsglob.h | 5 +++- fs/cifs/file.c | 74 ++++++++++++++++++++++++++++++---------------- 3 files changed, 65 insertions(+), 27 deletions(-)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index 1a135d1b85bd..07d8ace61f77 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;
@@ -1554,11 +1555,18 @@ 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(); @@ -1624,6 +1632,8 @@ out_unreg_fscache: 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: @@ -1653,6 +1663,7 @@ 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 5d2dd04b55a6..f55e53486e74 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -1265,6 +1265,7 @@ struct cifsFileInfo { struct mutex fh_mutex; /* prevents reopen race after dead ses*/ struct cifs_search_info srch_inf; struct work_struct oplock_break; /* work for oplock breaks */ + struct work_struct put; /* work for the final part of _put */ };
struct cifs_io_parms { @@ -1370,7 +1371,8 @@ cifsFileInfo_get_locked(struct cifsFileInfo *cifs_file) }
struct cifsFileInfo *cifsFileInfo_get(struct cifsFileInfo *cifs_file); -void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_hdlr); +void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_hdlr, + bool offload); void cifsFileInfo_put(struct cifsFileInfo *cifs_file);
#define CIFS_CACHE_READ_FLG 1 @@ -1908,6 +1910,7 @@ 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 c32650f14c9b..969543034b4d 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -288,6 +288,8 @@ cifs_down_write(struct rw_semaphore *sem) msleep(10); }
+static void cifsFileInfo_put_work(struct work_struct *work); + struct cifsFileInfo * cifs_new_fileinfo(struct cifs_fid *fid, struct file *file, struct tcon_link *tlink, __u32 oplock) @@ -322,6 +324,7 @@ cifs_new_fileinfo(struct cifs_fid *fid, struct file *file, cfile->invalidHandle = false; cfile->tlink = cifs_get_tlink(tlink); INIT_WORK(&cfile->oplock_break, cifs_oplock_break); + INIT_WORK(&cfile->put, cifsFileInfo_put_work); mutex_init(&cfile->fh_mutex); spin_lock_init(&cfile->file_info_lock);
@@ -376,6 +379,41 @@ cifsFileInfo_get(struct cifsFileInfo *cifs_file) return cifs_file; }
+static void cifsFileInfo_put_final(struct cifsFileInfo *cifs_file) +{ + struct inode *inode = d_inode(cifs_file->dentry); + struct cifsInodeInfo *cifsi = CIFS_I(inode); + struct cifsLockInfo *li, *tmp; + struct super_block *sb = inode->i_sb; + + /* + * Delete any outstanding lock records. We'll lose them when the file + * is closed anyway. + */ + cifs_down_write(&cifsi->lock_sem); + list_for_each_entry_safe(li, tmp, &cifs_file->llist->locks, llist) { + list_del(&li->llist); + cifs_del_lock_waiters(li); + kfree(li); + } + list_del(&cifs_file->llist->llist); + kfree(cifs_file->llist); + up_write(&cifsi->lock_sem); + + cifs_put_tlink(cifs_file->tlink); + dput(cifs_file->dentry); + cifs_sb_deactive(sb); + kfree(cifs_file); +} + +static void cifsFileInfo_put_work(struct work_struct *work) +{ + struct cifsFileInfo *cifs_file = container_of(work, + struct cifsFileInfo, put); + + cifsFileInfo_put_final(cifs_file); +} + /** * cifsFileInfo_put - release a reference of file priv data * @@ -383,15 +421,15 @@ cifsFileInfo_get(struct cifsFileInfo *cifs_file) */ void cifsFileInfo_put(struct cifsFileInfo *cifs_file) { - _cifsFileInfo_put(cifs_file, true); + _cifsFileInfo_put(cifs_file, true, 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. + * server. Must be called without holding tcon->open_file_lock, + * cinode->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 @@ -399,7 +437,8 @@ void cifsFileInfo_put(struct cifsFileInfo *cifs_file) * oplock break handler, you need to pass false. * */ -void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler) +void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, + bool wait_oplock_handler, bool offload) { struct inode *inode = d_inode(cifs_file->dentry); struct cifs_tcon *tcon = tlink_tcon(cifs_file->tlink); @@ -407,7 +446,6 @@ void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler) struct cifsInodeInfo *cifsi = CIFS_I(inode); struct super_block *sb = inode->i_sb; struct cifs_sb_info *cifs_sb = CIFS_SB(sb); - struct cifsLockInfo *li, *tmp; struct cifs_fid fid; struct cifs_pending_open open; bool oplock_break_cancelled; @@ -468,24 +506,10 @@ void _cifsFileInfo_put(struct cifsFileInfo *cifs_file, bool wait_oplock_handler)
cifs_del_pending_open(&open);
- /* - * Delete any outstanding lock records. We'll lose them when the file - * is closed anyway. - */ - cifs_down_write(&cifsi->lock_sem); - list_for_each_entry_safe(li, tmp, &cifs_file->llist->locks, llist) { - list_del(&li->llist); - cifs_del_lock_waiters(li); - kfree(li); - } - list_del(&cifs_file->llist->llist); - kfree(cifs_file->llist); - up_write(&cifsi->lock_sem); - - cifs_put_tlink(cifs_file->tlink); - dput(cifs_file->dentry); - cifs_sb_deactive(sb); - kfree(cifs_file); + if (offload) + queue_work(fileinfo_put_wq, &cifs_file->put); + else + cifsFileInfo_put_final(cifs_file); }
int cifs_open(struct inode *inode, struct file *file) @@ -816,7 +840,7 @@ reopen_error_exit: int cifs_close(struct inode *inode, struct file *file) { if (file->private_data != NULL) { - cifsFileInfo_put(file->private_data); + _cifsFileInfo_put(file->private_data, true, false); file->private_data = NULL; }
@@ -4688,7 +4712,7 @@ void cifs_oplock_break(struct work_struct *work) cinode); cifs_dbg(FYI, "Oplock release rc = %d\n", rc); } - _cifsFileInfo_put(cfile, false /* do not wait for ourself */); + _cifsFileInfo_put(cfile, false /* do not wait for ourself */, false); cifs_done_oplock_break(cinode); }