<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/block, branch v4.14.95</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>nbd: Use set_blocksize() to set device blocksize</title>
<updated>2019-01-23T07:09:51+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2019-01-14T08:48:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c2912ca3f893a14fd24a6cad165acf61f4d7bc01'/>
<id>c2912ca3f893a14fd24a6cad165acf61f4d7bc01</id>
<content type='text'>
commit c8a83a6b54d0ca078de036aafb3f6af58c1dc5eb upstream.

NBD can update block device block size implicitely through
bd_set_size(). Make it explicitely set blocksize with set_blocksize() as
this behavior of bd_set_size() is going away.

CC: Josef Bacik &lt;jbacik@fb.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit c8a83a6b54d0ca078de036aafb3f6af58c1dc5eb upstream.

NBD can update block device block size implicitely through
bd_set_size(). Make it explicitely set blocksize with set_blocksize() as
this behavior of bd_set_size() is going away.

CC: Josef Bacik &lt;jbacik@fb.com&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>loop: drop caches if offset or block_size are changed</title>
<updated>2019-01-23T07:09:51+00:00</updated>
<author>
<name>Jaegeuk Kim</name>
<email>jaegeuk@kernel.org</email>
</author>
<published>2019-01-10T03:17:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=45662e4b717c7579e49a5e5c5086c543d15af0c4'/>
<id>45662e4b717c7579e49a5e5c5086c543d15af0c4</id>
<content type='text'>
commit 5db470e229e22b7eda6e23b5566e532c96fb5bc3 upstream.

If we don't drop caches used in old offset or block_size, we can get old data
from new offset/block_size, which gives unexpected data to user.

For example, Martijn found a loopback bug in the below scenario.
1) LOOP_SET_FD loads first two pages on loop file
2) LOOP_SET_STATUS64 changes the offset on the loop file
3) mount is failed due to the cached pages having wrong superblock

Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: linux-block@vger.kernel.org
Reported-by: Martijn Coenen &lt;maco@google.com&gt;
Reviewed-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 5db470e229e22b7eda6e23b5566e532c96fb5bc3 upstream.

If we don't drop caches used in old offset or block_size, we can get old data
from new offset/block_size, which gives unexpected data to user.

For example, Martijn found a loopback bug in the below scenario.
1) LOOP_SET_FD loads first two pages on loop file
2) LOOP_SET_STATUS64 changes the offset on the loop file
3) mount is failed due to the cached pages having wrong superblock

Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: linux-block@vger.kernel.org
Reported-by: Martijn Coenen &lt;maco@google.com&gt;
Reviewed-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Jaegeuk Kim &lt;jaegeuk@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>loop: Fix double mutex_unlock(&amp;loop_ctl_mutex) in loop_control_ioctl()</title>
<updated>2019-01-23T07:09:51+00:00</updated>
<author>
<name>Tetsuo Handa</name>
<email>penguin-kernel@I-love.SAKURA.ne.jp</email>
</author>
<published>2018-11-12T15:42:14+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=d2762edcb6af99fc9322bab0b1d4e71a427760e8'/>
<id>d2762edcb6af99fc9322bab0b1d4e71a427760e8</id>
<content type='text'>
commit 628bd85947091830a8c4872adfd5ed1d515a9cf2 upstream.

Commit 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex") forgot to
remove mutex_unlock(&amp;loop_ctl_mutex) from loop_control_ioctl() when
replacing loop_index_mutex with loop_ctl_mutex.

Fixes: 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex")
Reported-by: syzbot &lt;syzbot+c0138741c2290fc5e63f@syzkaller.appspotmail.com&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 628bd85947091830a8c4872adfd5ed1d515a9cf2 upstream.

Commit 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex") forgot to
remove mutex_unlock(&amp;loop_ctl_mutex) from loop_control_ioctl() when
replacing loop_index_mutex with loop_ctl_mutex.

Fixes: 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex")
Reported-by: syzbot &lt;syzbot+c0138741c2290fc5e63f@syzkaller.appspotmail.com&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>loop: Get rid of loop_index_mutex</title>
<updated>2019-01-23T07:09:51+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2018-11-08T13:01:04+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c1e63df4f30c3918476ac9bc594355b0e9629893'/>
<id>c1e63df4f30c3918476ac9bc594355b0e9629893</id>
<content type='text'>
commit 0a42e99b58a208839626465af194cfe640ef9493 upstream.

Now that loop_ctl_mutex is global, just get rid of loop_index_mutex as
there is no good reason to keep these two separate and it just
complicates the locking.

Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 0a42e99b58a208839626465af194cfe640ef9493 upstream.

Now that loop_ctl_mutex is global, just get rid of loop_index_mutex as
there is no good reason to keep these two separate and it just
complicates the locking.

Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>loop: Fold __loop_release into loop_release</title>
<updated>2019-01-23T07:09:51+00:00</updated>
<author>
<name>Jan Kara</name>
<email>jack@suse.cz</email>
</author>
<published>2018-11-08T13:01:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f1e81ba8a3fa56dcc48828869b392b29559a0ac3'/>
<id>f1e81ba8a3fa56dcc48828869b392b29559a0ac3</id>
<content type='text'>
commit 967d1dc144b50ad005e5eecdfadfbcfb399ffff6 upstream.

__loop_release() has a single call site. Fold it there. This is
currently not a huge win but it will make following replacement of
loop_index_mutex more obvious.

Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 967d1dc144b50ad005e5eecdfadfbcfb399ffff6 upstream.

__loop_release() has a single call site. Fold it there. This is
currently not a huge win but it will make following replacement of
loop_index_mutex more obvious.

Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>block/loop: Use global lock for ioctl() operation.</title>
<updated>2019-01-23T07:09:51+00:00</updated>
<author>
<name>Tetsuo Handa</name>
<email>penguin-kernel@I-love.SAKURA.ne.jp</email>
</author>
<published>2018-11-08T13:01:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=57da9a9742200f391d1cf93fea389f7ddc25ec9a'/>
<id>57da9a9742200f391d1cf93fea389f7ddc25ec9a</id>
<content type='text'>
commit 310ca162d779efee8a2dc3731439680f3e9c1e86 upstream.

syzbot is reporting NULL pointer dereference [1] which is caused by
race condition between ioctl(loop_fd, LOOP_CLR_FD, 0) versus
ioctl(other_loop_fd, LOOP_SET_FD, loop_fd) due to traversing other
loop devices at loop_validate_file() without holding corresponding
lo-&gt;lo_ctl_mutex locks.

Since ioctl() request on loop devices is not frequent operation, we don't
need fine grained locking. Let's use global lock in order to allow safe
traversal at loop_validate_file().

Note that syzbot is also reporting circular locking dependency between
bdev-&gt;bd_mutex and lo-&gt;lo_ctl_mutex [2] which is caused by calling
blkdev_reread_part() with lock held. This patch does not address it.

[1] https://syzkaller.appspot.com/bug?id=f3cfe26e785d85f9ee259f385515291d21bd80a3
[2] https://syzkaller.appspot.com/bug?id=bf154052f0eea4bc7712499e4569505907d15889

Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Reported-by: syzbot &lt;syzbot+bf89c128e05dd6c62523@syzkaller.appspotmail.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 310ca162d779efee8a2dc3731439680f3e9c1e86 upstream.

syzbot is reporting NULL pointer dereference [1] which is caused by
race condition between ioctl(loop_fd, LOOP_CLR_FD, 0) versus
ioctl(other_loop_fd, LOOP_SET_FD, loop_fd) due to traversing other
loop devices at loop_validate_file() without holding corresponding
lo-&gt;lo_ctl_mutex locks.

Since ioctl() request on loop devices is not frequent operation, we don't
need fine grained locking. Let's use global lock in order to allow safe
traversal at loop_validate_file().

Note that syzbot is also reporting circular locking dependency between
bdev-&gt;bd_mutex and lo-&gt;lo_ctl_mutex [2] which is caused by calling
blkdev_reread_part() with lock held. This patch does not address it.

[1] https://syzkaller.appspot.com/bug?id=f3cfe26e785d85f9ee259f385515291d21bd80a3
[2] https://syzkaller.appspot.com/bug?id=bf154052f0eea4bc7712499e4569505907d15889

Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Reported-by: syzbot &lt;syzbot+bf89c128e05dd6c62523@syzkaller.appspotmail.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>block/loop: Don't grab "struct file" for vfs_getattr() operation.</title>
<updated>2019-01-23T07:09:51+00:00</updated>
<author>
<name>Tetsuo Handa</name>
<email>penguin-kernel@I-love.SAKURA.ne.jp</email>
</author>
<published>2018-11-08T13:01:01+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=06ee6e217586a1944cb9d50b3a2141cb060b7128'/>
<id>06ee6e217586a1944cb9d50b3a2141cb060b7128</id>
<content type='text'>
commit b1ab5fa309e6c49e4e06270ec67dd7b3e9971d04 upstream.

vfs_getattr() needs "struct path" rather than "struct file".
Let's use path_get()/path_put() rather than get_file()/fput().

Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b1ab5fa309e6c49e4e06270ec67dd7b3e9971d04 upstream.

vfs_getattr() needs "struct path" rather than "struct file".
Let's use path_get()/path_put() rather than get_file()/fput().

Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>rbd: don't return 0 on unmap if RBD_DEV_FLAG_REMOVING is set</title>
<updated>2019-01-16T21:07:12+00:00</updated>
<author>
<name>Ilya Dryomov</name>
<email>idryomov@gmail.com</email>
</author>
<published>2019-01-08T18:47:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=022ce60cc621c84df6d0272984e791f60983fd7a'/>
<id>022ce60cc621c84df6d0272984e791f60983fd7a</id>
<content type='text'>
commit 85f5a4d666fd9be73856ed16bb36c5af5b406b29 upstream.

There is a window between when RBD_DEV_FLAG_REMOVING is set and when
the device is removed from rbd_dev_list.  During this window, we set
"already" and return 0.

Returning 0 from write(2) can confuse userspace tools because
0 indicates that nothing was written.  In particular, "rbd unmap"
will retry the write multiple times a second:

  10:28:05.463299 write(4, "0", 1)        = 0
  10:28:05.463509 write(4, "0", 1)        = 0
  10:28:05.463720 write(4, "0", 1)        = 0
  10:28:05.463942 write(4, "0", 1)        = 0
  10:28:05.464155 write(4, "0", 1)        = 0

Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov &lt;idryomov@gmail.com&gt;
Tested-by: Dongsheng Yang &lt;dongsheng.yang@easystack.cn&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 85f5a4d666fd9be73856ed16bb36c5af5b406b29 upstream.

There is a window between when RBD_DEV_FLAG_REMOVING is set and when
the device is removed from rbd_dev_list.  During this window, we set
"already" and return 0.

Returning 0 from write(2) can confuse userspace tools because
0 indicates that nothing was written.  In particular, "rbd unmap"
will retry the write multiple times a second:

  10:28:05.463299 write(4, "0", 1)        = 0
  10:28:05.463509 write(4, "0", 1)        = 0
  10:28:05.463720 write(4, "0", 1)        = 0
  10:28:05.463942 write(4, "0", 1)        = 0
  10:28:05.464155 write(4, "0", 1)        = 0

Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov &lt;idryomov@gmail.com&gt;
Tested-by: Dongsheng Yang &lt;dongsheng.yang@easystack.cn&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>zram: fix double free backing device</title>
<updated>2019-01-13T09:01:02+00:00</updated>
<author>
<name>Minchan Kim</name>
<email>minchan@kernel.org</email>
</author>
<published>2018-12-28T08:36:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ce8daa28a1d53dcf4258cff2b559d7ad37325dfa'/>
<id>ce8daa28a1d53dcf4258cff2b559d7ad37325dfa</id>
<content type='text'>
commit 5547932dc67a48713eece4fa4703bfdf0cfcb818 upstream.

If blkdev_get fails, we shouldn't do blkdev_put.  Otherwise, kernel emits
below log.  This patch fixes it.

  WARNING: CPU: 0 PID: 1893 at fs/block_dev.c:1828 blkdev_put+0x105/0x120
  Modules linked in:
  CPU: 0 PID: 1893 Comm: swapoff Not tainted 4.19.0+ #453
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
  RIP: 0010:blkdev_put+0x105/0x120
  Call Trace:
    __x64_sys_swapoff+0x46d/0x490
    do_syscall_64+0x5a/0x190
    entry_SYSCALL_64_after_hwframe+0x49/0xbe
  irq event stamp: 4466
  hardirqs last  enabled at (4465):  __free_pages_ok+0x1e3/0x490
  hardirqs last disabled at (4466):  trace_hardirqs_off_thunk+0x1a/0x1c
  softirqs last  enabled at (3420):  __do_softirq+0x333/0x446
  softirqs last disabled at (3407):  irq_exit+0xd1/0xe0

Link: http://lkml.kernel.org/r/20181127055429.251614-3-minchan@kernel.org
Signed-off-by: Minchan Kim &lt;minchan@kernel.org&gt;
Reviewed-by: Sergey Senozhatsky &lt;sergey.senozhatsky@gmail.com&gt;
Reviewed-by: Joey Pabalinas &lt;joeypabalinas@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;	[4.14+]
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 5547932dc67a48713eece4fa4703bfdf0cfcb818 upstream.

If blkdev_get fails, we shouldn't do blkdev_put.  Otherwise, kernel emits
below log.  This patch fixes it.

  WARNING: CPU: 0 PID: 1893 at fs/block_dev.c:1828 blkdev_put+0x105/0x120
  Modules linked in:
  CPU: 0 PID: 1893 Comm: swapoff Not tainted 4.19.0+ #453
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
  RIP: 0010:blkdev_put+0x105/0x120
  Call Trace:
    __x64_sys_swapoff+0x46d/0x490
    do_syscall_64+0x5a/0x190
    entry_SYSCALL_64_after_hwframe+0x49/0xbe
  irq event stamp: 4466
  hardirqs last  enabled at (4465):  __free_pages_ok+0x1e3/0x490
  hardirqs last disabled at (4466):  trace_hardirqs_off_thunk+0x1a/0x1c
  softirqs last  enabled at (3420):  __do_softirq+0x333/0x446
  softirqs last disabled at (3407):  irq_exit+0xd1/0xe0

Link: http://lkml.kernel.org/r/20181127055429.251614-3-minchan@kernel.org
Signed-off-by: Minchan Kim &lt;minchan@kernel.org&gt;
Reviewed-by: Sergey Senozhatsky &lt;sergey.senozhatsky@gmail.com&gt;
Reviewed-by: Joey Pabalinas &lt;joeypabalinas@gmail.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;	[4.14+]
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>floppy: fix race condition in __floppy_read_block_0()</title>
<updated>2018-12-01T08:42:53+00:00</updated>
<author>
<name>Jens Axboe</name>
<email>axboe@kernel.dk</email>
</author>
<published>2018-11-09T22:58:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5565c30a0bc770764cd085db881bc7a9f5e9d63c'/>
<id>5565c30a0bc770764cd085db881bc7a9f5e9d63c</id>
<content type='text'>
[ Upstream commit de7b75d82f70c5469675b99ad632983c50b6f7e7 ]

LKP recently reported a hang at bootup in the floppy code:

[  245.678853] INFO: task mount:580 blocked for more than 120 seconds.
[  245.679906]       Tainted: G                T 4.19.0-rc6-00172-ga9f38e1 #1
[  245.680959] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  245.682181] mount           D 6372   580      1 0x00000004
[  245.683023] Call Trace:
[  245.683425]  __schedule+0x2df/0x570
[  245.683975]  schedule+0x2d/0x80
[  245.684476]  schedule_timeout+0x19d/0x330
[  245.685090]  ? wait_for_common+0xa5/0x170
[  245.685735]  wait_for_common+0xac/0x170
[  245.686339]  ? do_sched_yield+0x90/0x90
[  245.686935]  wait_for_completion+0x12/0x20
[  245.687571]  __floppy_read_block_0+0xfb/0x150
[  245.688244]  ? floppy_resume+0x40/0x40
[  245.688844]  floppy_revalidate+0x20f/0x240
[  245.689486]  check_disk_change+0x43/0x60
[  245.690087]  floppy_open+0x1ea/0x360
[  245.690653]  __blkdev_get+0xb4/0x4d0
[  245.691212]  ? blkdev_get+0x1db/0x370
[  245.691777]  blkdev_get+0x1f3/0x370
[  245.692351]  ? path_put+0x15/0x20
[  245.692871]  ? lookup_bdev+0x4b/0x90
[  245.693539]  blkdev_get_by_path+0x3d/0x80
[  245.694165]  mount_bdev+0x2a/0x190
[  245.694695]  squashfs_mount+0x10/0x20
[  245.695271]  ? squashfs_alloc_inode+0x30/0x30
[  245.695960]  mount_fs+0xf/0x90
[  245.696451]  vfs_kern_mount+0x43/0x130
[  245.697036]  do_mount+0x187/0xc40
[  245.697563]  ? memdup_user+0x28/0x50
[  245.698124]  ksys_mount+0x60/0xc0
[  245.698639]  sys_mount+0x19/0x20
[  245.699167]  do_int80_syscall_32+0x61/0x130
[  245.699813]  entry_INT80_32+0xc7/0xc7

showing that we never complete that read request. The reason is that
the completion setup is racy - it initializes the completion event
AFTER submitting the IO, which means that the IO could complete
before/during the init. If it does, we are passing garbage to
complete() and we may sleep forever waiting for the event to
occur.

Fixes: 7b7b68bba5ef ("floppy: bail out in open() if drive is not responding to block0 read")
Reviewed-by: Omar Sandoval &lt;osandov@fb.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
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<pre>
[ Upstream commit de7b75d82f70c5469675b99ad632983c50b6f7e7 ]

LKP recently reported a hang at bootup in the floppy code:

[  245.678853] INFO: task mount:580 blocked for more than 120 seconds.
[  245.679906]       Tainted: G                T 4.19.0-rc6-00172-ga9f38e1 #1
[  245.680959] "echo 0 &gt; /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  245.682181] mount           D 6372   580      1 0x00000004
[  245.683023] Call Trace:
[  245.683425]  __schedule+0x2df/0x570
[  245.683975]  schedule+0x2d/0x80
[  245.684476]  schedule_timeout+0x19d/0x330
[  245.685090]  ? wait_for_common+0xa5/0x170
[  245.685735]  wait_for_common+0xac/0x170
[  245.686339]  ? do_sched_yield+0x90/0x90
[  245.686935]  wait_for_completion+0x12/0x20
[  245.687571]  __floppy_read_block_0+0xfb/0x150
[  245.688244]  ? floppy_resume+0x40/0x40
[  245.688844]  floppy_revalidate+0x20f/0x240
[  245.689486]  check_disk_change+0x43/0x60
[  245.690087]  floppy_open+0x1ea/0x360
[  245.690653]  __blkdev_get+0xb4/0x4d0
[  245.691212]  ? blkdev_get+0x1db/0x370
[  245.691777]  blkdev_get+0x1f3/0x370
[  245.692351]  ? path_put+0x15/0x20
[  245.692871]  ? lookup_bdev+0x4b/0x90
[  245.693539]  blkdev_get_by_path+0x3d/0x80
[  245.694165]  mount_bdev+0x2a/0x190
[  245.694695]  squashfs_mount+0x10/0x20
[  245.695271]  ? squashfs_alloc_inode+0x30/0x30
[  245.695960]  mount_fs+0xf/0x90
[  245.696451]  vfs_kern_mount+0x43/0x130
[  245.697036]  do_mount+0x187/0xc40
[  245.697563]  ? memdup_user+0x28/0x50
[  245.698124]  ksys_mount+0x60/0xc0
[  245.698639]  sys_mount+0x19/0x20
[  245.699167]  do_int80_syscall_32+0x61/0x130
[  245.699813]  entry_INT80_32+0xc7/0xc7

showing that we never complete that read request. The reason is that
the completion setup is racy - it initializes the completion event
AFTER submitting the IO, which means that the IO could complete
before/during the init. If it does, we are passing garbage to
complete() and we may sleep forever waiting for the event to
occur.

Fixes: 7b7b68bba5ef ("floppy: bail out in open() if drive is not responding to block0 read")
Reviewed-by: Omar Sandoval &lt;osandov@fb.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
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