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cifs: move cifsFileInfo_put logic into a work-queue 

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 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@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>
This commit is contained in:
Ronnie Sahlberg 2019-11-03 13:06:37 +10:00 committed by Steve French
parent d70e9fa558
commit 32546a9586
3 changed files with 65 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
fs/cifs/cifsfs.c
View File

@ -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;
@ -1561,11 +1562,18 @@ 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();
@ -1631,6 +1639,8 @@ 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:
@ -1660,6 +1670,7 @@ 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();
}

5
fs/cifs/cifsglob.h
View File

@ -1308,6 +1308,7 @@ 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 {
@ -1413,7 +1414,8 @@ 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
@ -1953,6 +1955,7 @@ 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;

74
fs/cifs/file.c
View File

@ -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)
@ -325,6 +327,7 @@ 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);
@ -375,6 +378,41 @@ 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
*
@ -382,15 +420,15 @@ 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
@ -398,7 +436,8 @@ 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);
@ -406,7 +445,6 @@ 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;
@ -467,24 +505,10 @@ 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)
@ -815,7 +839,7 @@ cifs_reopen_file(struct cifsFileInfo *cfile, bool can_flush)
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;
}
@ -4749,7 +4773,7 @@ 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);
}