<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/fs, branch v3.13-rc3</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge git://git.kvack.org/~bcrl/aio-next</title>
<updated>2013-12-06T16:32:59+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-12-06T16:32:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=c537aba00e3f1df8ce6c7c9fcb98b82c0c2d1d2c'/>
<id>c537aba00e3f1df8ce6c7c9fcb98b82c0c2d1d2c</id>
<content type='text'>
Pull aio fix from Benjamin LaHaise:
 "AIO fix from Gu Zheng that fixes a GPF that Dave Jones uncovered with
  trinity"

* git://git.kvack.org/~bcrl/aio-next:
  aio: clean up aio ring in the fail path
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull aio fix from Benjamin LaHaise:
 "AIO fix from Gu Zheng that fixes a GPF that Dave Jones uncovered with
  trinity"

* git://git.kvack.org/~bcrl/aio-next:
  aio: clean up aio ring in the fail path
</pre>
</div>
</content>
</entry>
<entry>
<title>aio: clean up aio ring in the fail path</title>
<updated>2013-12-06T15:22:55+00:00</updated>
<author>
<name>Gu Zheng</name>
<email>guz.fnst@cn.fujitsu.com</email>
</author>
<published>2013-12-04T10:19:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=d1b9432712a25eeb06114fb4b587133525a47de5'/>
<id>d1b9432712a25eeb06114fb4b587133525a47de5</id>
<content type='text'>
Clean up the aio ring file in the fail path of aio_setup_ring
and ioctx_alloc. And maybe it can fix the GPF issue reported by
Dave Jones:
https://lkml.org/lkml/2013/11/25/898

Signed-off-by: Gu Zheng &lt;guz.fnst@cn.fujitsu.com&gt;
Signed-off-by: Benjamin LaHaise &lt;bcrl@kvack.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Clean up the aio ring file in the fail path of aio_setup_ring
and ioctx_alloc. And maybe it can fix the GPF issue reported by
Dave Jones:
https://lkml.org/lkml/2013/11/25/898

Signed-off-by: Gu Zheng &lt;guz.fnst@cn.fujitsu.com&gt;
Signed-off-by: Benjamin LaHaise &lt;bcrl@kvack.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'pm-3.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm</title>
<updated>2013-12-06T02:26:40+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-12-06T02:26:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=002acf1fc16cf60e60345bd68e03734628505b83'/>
<id>002acf1fc16cf60e60345bd68e03734628505b83</id>
<content type='text'>
Pull power management fixes from Rafael Wysocki:

 - cpufreq regression fix from Bjørn Mork restoring the pre-3.12
   behavior of the framework during system suspend/hibernation to avoid
   garbage sysfs files from being left behind in case of a suspend error

 - PNP regression fix to restore the correct states of devices after
   resume from hibernation broken in 3.12.  From Dmitry Torokhov.

 - cpuidle fix to prevent cpuidle device unregistration from crashing
   due to a NULL pointer dereference if cpuidle has been disabled from
   the kernel command line.  From Konrad Rzeszutek Wilk.

 - intel_idle fix for the C6 state definition on Intel Avoton/Rangeley
   processors from Arne Bockholdt.

 - Power capping framework fix to make the energy_uj sysfs attribute
   work in accordance with the documentation.  From Srinivas Pandruvada.

 - epoll fix to make it ignore the EPOLLWAKEUP flag if the kernel has
   been compiled with CONFIG_PM_SLEEP unset (in which case that flag
   should not have any effect).  From Amit Pundir.

 - cpufreq fix to prevent governor sysfs files from being lost over
   system suspend/resume in some (arguably unusual) situations.  From
   Viresh Kumar.

* tag 'pm-3.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PowerCap: Fix mode for energy counter
  PNP: fix restoring devices after hibernation
  cpuidle: Check for dev before deregistering it.
  epoll: drop EPOLLWAKEUP if PM_SLEEP is disabled
  cpufreq: fix garbage kobjects on errors during suspend/resume
  cpufreq: suspend governors on system suspend/hibernate
  intel_idle: Fixed C6 state on Avoton/Rangeley processors
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull power management fixes from Rafael Wysocki:

 - cpufreq regression fix from Bjørn Mork restoring the pre-3.12
   behavior of the framework during system suspend/hibernation to avoid
   garbage sysfs files from being left behind in case of a suspend error

 - PNP regression fix to restore the correct states of devices after
   resume from hibernation broken in 3.12.  From Dmitry Torokhov.

 - cpuidle fix to prevent cpuidle device unregistration from crashing
   due to a NULL pointer dereference if cpuidle has been disabled from
   the kernel command line.  From Konrad Rzeszutek Wilk.

 - intel_idle fix for the C6 state definition on Intel Avoton/Rangeley
   processors from Arne Bockholdt.

 - Power capping framework fix to make the energy_uj sysfs attribute
   work in accordance with the documentation.  From Srinivas Pandruvada.

 - epoll fix to make it ignore the EPOLLWAKEUP flag if the kernel has
   been compiled with CONFIG_PM_SLEEP unset (in which case that flag
   should not have any effect).  From Amit Pundir.

 - cpufreq fix to prevent governor sysfs files from being lost over
   system suspend/resume in some (arguably unusual) situations.  From
   Viresh Kumar.

* tag 'pm-3.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PowerCap: Fix mode for energy counter
  PNP: fix restoring devices after hibernation
  cpuidle: Check for dev before deregistering it.
  epoll: drop EPOLLWAKEUP if PM_SLEEP is disabled
  cpufreq: fix garbage kobjects on errors during suspend/resume
  cpufreq: suspend governors on system suspend/hibernate
  intel_idle: Fixed C6 state on Avoton/Rangeley processors
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'for-linus' of git://git.kernel.dk/linux-block</title>
<updated>2013-12-05T23:33:27+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-12-05T23:33:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=5ee540613db504a10e15fafaf4c08cac96aa1823'/>
<id>5ee540613db504a10e15fafaf4c08cac96aa1823</id>
<content type='text'>
Pull block layer fixes from Jens Axboe:
 "A small collection of fixes for the current series. It contains:

   - A fix for a use-after-free of a request in blk-mq.  From Ming Lei

   - A fix for a blk-mq bug that could attempt to dereference a NULL rq
     if allocation failed

   - Two xen-blkfront small fixes

   - Cleanup of submit_bio_wait() type uses in the kernel, unifying
     that.  From Kent

   - A fix for 32-bit blkg_rwstat reading.  I apologize for this one
     looking mangled in the shortlog, it's entirely my fault for missing
     an empty line between the description and body of the text"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: fix use-after-free of request
  blk-mq: fix dereference of rq-&gt;mq_ctx if allocation fails
  block: xen-blkfront: Fix possible NULL ptr dereference
  xen-blkfront: Silence pfn maybe-uninitialized warning
  block: submit_bio_wait() conversions
  Update of blkg_stat and blkg_rwstat may happen in bh context
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block layer fixes from Jens Axboe:
 "A small collection of fixes for the current series. It contains:

   - A fix for a use-after-free of a request in blk-mq.  From Ming Lei

   - A fix for a blk-mq bug that could attempt to dereference a NULL rq
     if allocation failed

   - Two xen-blkfront small fixes

   - Cleanup of submit_bio_wait() type uses in the kernel, unifying
     that.  From Kent

   - A fix for 32-bit blkg_rwstat reading.  I apologize for this one
     looking mangled in the shortlog, it's entirely my fault for missing
     an empty line between the description and body of the text"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: fix use-after-free of request
  blk-mq: fix dereference of rq-&gt;mq_ctx if allocation fails
  block: xen-blkfront: Fix possible NULL ptr dereference
  xen-blkfront: Silence pfn maybe-uninitialized warning
  block: submit_bio_wait() conversions
  Update of blkg_stat and blkg_rwstat may happen in bh context
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'nfs-for-3.13-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs</title>
<updated>2013-12-05T21:05:48+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-12-05T21:05:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=29be6345bbaec8502a70c4e2204d5818b48c4e8f'/>
<id>29be6345bbaec8502a70c4e2204d5818b48c4e8f</id>
<content type='text'>
Pull NFS client bugfixes from Trond Myklebust:
 - Stable fix for a NFSv4.1 delegation and state recovery deadlock
 - Stable fix for a loop on irrecoverable errors when returning
   delegations
 - Fix a 3-way deadlock between layoutreturn, open, and state recovery
 - Update the MAINTAINERS file with contact information for Trond
   Myklebust
 - Close needs to handle NFS4ERR_ADMIN_REVOKED
 - Enabling v4.2 should not recompile nfsd and lockd
 - Fix a couple of compile warnings

* tag 'nfs-for-3.13-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  nfs: fix do_div() warning by instead using sector_div()
  MAINTAINERS: Update contact information for Trond Myklebust
  NFSv4.1: Prevent a 3-way deadlock between layoutreturn, open and state recovery
  SUNRPC: do not fail gss proc NULL calls with EACCES
  NFSv4: close needs to handle NFS4ERR_ADMIN_REVOKED
  NFSv4: Update list of irrecoverable errors on DELEGRETURN
  NFSv4 wait on recovery for async session errors
  NFS: Fix a warning in nfs_setsecurity
  NFS: Enabling v4.2 should not recompile nfsd and lockd
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull NFS client bugfixes from Trond Myklebust:
 - Stable fix for a NFSv4.1 delegation and state recovery deadlock
 - Stable fix for a loop on irrecoverable errors when returning
   delegations
 - Fix a 3-way deadlock between layoutreturn, open, and state recovery
 - Update the MAINTAINERS file with contact information for Trond
   Myklebust
 - Close needs to handle NFS4ERR_ADMIN_REVOKED
 - Enabling v4.2 should not recompile nfsd and lockd
 - Fix a couple of compile warnings

* tag 'nfs-for-3.13-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  nfs: fix do_div() warning by instead using sector_div()
  MAINTAINERS: Update contact information for Trond Myklebust
  NFSv4.1: Prevent a 3-way deadlock between layoutreturn, open and state recovery
  SUNRPC: do not fail gss proc NULL calls with EACCES
  NFSv4: close needs to handle NFS4ERR_ADMIN_REVOKED
  NFSv4: Update list of irrecoverable errors on DELEGRETURN
  NFSv4 wait on recovery for async session errors
  NFS: Fix a warning in nfs_setsecurity
  NFS: Enabling v4.2 should not recompile nfsd and lockd
</pre>
</div>
</content>
</entry>
<entry>
<title>nfs: fix do_div() warning by instead using sector_div()</title>
<updated>2013-12-04T17:57:37+00:00</updated>
<author>
<name>Helge Deller</name>
<email>deller@gmx.de</email>
</author>
<published>2013-12-02T18:59:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3873d064b8538686bbbd4b858dc8a07db1f7f43a'/>
<id>3873d064b8538686bbbd4b858dc8a07db1f7f43a</id>
<content type='text'>
When compiling a 32bit kernel with CONFIG_LBDAF=n the compiler complains like
shown below.  Fix this warning by instead using sector_div() which is provided
by the kernel.h header file.

fs/nfs/blocklayout/extents.c: In function ‘normalize’:
include/asm-generic/div64.h:43:28: warning: comparison of distinct pointer types lacks a cast [enabled by default]
fs/nfs/blocklayout/extents.c:47:13: note: in expansion of macro ‘do_div’
nfs/blocklayout/extents.c:47:2: warning: right shift count &gt;= width of type [enabled by default]
fs/nfs/blocklayout/extents.c:47:2: warning: passing argument 1 of ‘__div64_32’ from incompatible pointer type [enabled by default]
include/asm-generic/div64.h:35:17: note: expected ‘uint64_t *’ but argument is of type ‘sector_t *’
 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);

Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
Signed-off-by: Trond Myklebust &lt;Trond.Myklebust@netapp.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When compiling a 32bit kernel with CONFIG_LBDAF=n the compiler complains like
shown below.  Fix this warning by instead using sector_div() which is provided
by the kernel.h header file.

fs/nfs/blocklayout/extents.c: In function ‘normalize’:
include/asm-generic/div64.h:43:28: warning: comparison of distinct pointer types lacks a cast [enabled by default]
fs/nfs/blocklayout/extents.c:47:13: note: in expansion of macro ‘do_div’
nfs/blocklayout/extents.c:47:2: warning: right shift count &gt;= width of type [enabled by default]
fs/nfs/blocklayout/extents.c:47:2: warning: passing argument 1 of ‘__div64_32’ from incompatible pointer type [enabled by default]
include/asm-generic/div64.h:35:17: note: expected ‘uint64_t *’ but argument is of type ‘sector_t *’
 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);

Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
Signed-off-by: Trond Myklebust &lt;Trond.Myklebust@netapp.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>NFSv4.1: Prevent a 3-way deadlock between layoutreturn, open and state recovery</title>
<updated>2013-12-04T17:32:19+00:00</updated>
<author>
<name>Trond Myklebust</name>
<email>Trond.Myklebust@netapp.com</email>
</author>
<published>2013-12-04T17:09:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=f22e5edd2244609aed3906207a62223e7707a34d'/>
<id>f22e5edd2244609aed3906207a62223e7707a34d</id>
<content type='text'>
Andy Adamson reports:

The state manager is recovering expired state and recovery OPENs are being
processed. If kswapd is pruning inodes at the same time, a deadlock can occur
when kswapd calls evict_inode on an NFSv4.1 inode with a layout, and the
resultant layoutreturn gets an error that the state mangager is to handle,
causing the layoutreturn to wait on the (NFS client) cl_rpcwaitq.

At the same time an open is waiting for the inode deletion to complete in
__wait_on_freeing_inode.

If the open is either the open called by the state manager, or an open from
the same open owner that is holding the NFSv4 sequence id which causes the
OPEN from the state manager to wait for the sequence id on the Seqid_waitqueue,
then the state is deadlocked with kswapd.

The fix is simply to have layoutreturn ignore all errors except NFS4ERR_DELAY.
We already know that layouts are dropped on all server reboots, and that
it has to be coded to deal with the "forgetful client model" that doesn't
send layoutreturns.

Reported-by: Andy Adamson &lt;andros@netapp.com&gt;
Link: http://lkml.kernel.org/r/1385402270-14284-1-git-send-email-andros@netapp.com
Signed-off-by: Trond Myklebust &lt;Trond.Myklebust@primarydata.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Andy Adamson reports:

The state manager is recovering expired state and recovery OPENs are being
processed. If kswapd is pruning inodes at the same time, a deadlock can occur
when kswapd calls evict_inode on an NFSv4.1 inode with a layout, and the
resultant layoutreturn gets an error that the state mangager is to handle,
causing the layoutreturn to wait on the (NFS client) cl_rpcwaitq.

At the same time an open is waiting for the inode deletion to complete in
__wait_on_freeing_inode.

If the open is either the open called by the state manager, or an open from
the same open owner that is holding the NFSv4 sequence id which causes the
OPEN from the state manager to wait for the sequence id on the Seqid_waitqueue,
then the state is deadlocked with kswapd.

The fix is simply to have layoutreturn ignore all errors except NFS4ERR_DELAY.
We already know that layouts are dropped on all server reboots, and that
it has to be coded to deal with the "forgetful client model" that doesn't
send layoutreturns.

Reported-by: Andy Adamson &lt;andros@netapp.com&gt;
Link: http://lkml.kernel.org/r/1385402270-14284-1-git-send-email-andros@netapp.com
Signed-off-by: Trond Myklebust &lt;Trond.Myklebust@primarydata.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'squashfs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next</title>
<updated>2013-12-04T16:54:00+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-12-04T16:54:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=278717909d47d86fbb20ab66dfeaa84560a2f8f2'/>
<id>278717909d47d86fbb20ab66dfeaa84560a2f8f2</id>
<content type='text'>
Pull squashfs bugfix from Phillip Lougher:
 "Just a single bug fix to the new "directly decompress into the page
  cache" code"

* tag 'squashfs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next:
  Squashfs: fix failure to unlock pages on decompress error
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull squashfs bugfix from Phillip Lougher:
 "Just a single bug fix to the new "directly decompress into the page
  cache" code"

* tag 'squashfs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/pkl/squashfs-next:
  Squashfs: fix failure to unlock pages on decompress error
</pre>
</div>
</content>
</entry>
<entry>
<title>epoll: drop EPOLLWAKEUP if PM_SLEEP is disabled</title>
<updated>2013-12-03T14:35:52+00:00</updated>
<author>
<name>Amit Pundir</name>
<email>amit.pundir@linaro.org</email>
</author>
<published>2013-11-15T07:26:31+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=95f19f658ce177387345b51bd48fed7b9cd7d4e8'/>
<id>95f19f658ce177387345b51bd48fed7b9cd7d4e8</id>
<content type='text'>
Drop EPOLLWAKEUP from epoll events mask if CONFIG_PM_SLEEP is disabled.

Signed-off-by: Amit Pundir &lt;amit.pundir@linaro.org&gt;
Cc: John Stultz &lt;john.stultz@linaro.org&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Drop EPOLLWAKEUP from epoll events mask if CONFIG_PM_SLEEP is disabled.

Signed-off-by: Amit Pundir &lt;amit.pundir@linaro.org&gt;
Cc: John Stultz &lt;john.stultz@linaro.org&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>vfs: fix subtle use-after-free of pipe_inode_info</title>
<updated>2013-12-02T17:44:51+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-12-02T17:44:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=b0d8d2292160bb63de1972361ebed100c64b5b37'/>
<id>b0d8d2292160bb63de1972361ebed100c64b5b37</id>
<content type='text'>
The pipe code was trying (and failing) to be very careful about freeing
the pipe info only after the last access, with a pattern like:

        spin_lock(&amp;inode-&gt;i_lock);
        if (!--pipe-&gt;files) {
                inode-&gt;i_pipe = NULL;
                kill = 1;
        }
        spin_unlock(&amp;inode-&gt;i_lock);
        __pipe_unlock(pipe);
        if (kill)
                free_pipe_info(pipe);

where the final freeing is done last.

HOWEVER.  The above is actually broken, because while the freeing is
done at the end, if we have two racing processes releasing the pipe
inode info, the one that *doesn't* free it will decrement the -&gt;files
count, and unlock the inode i_lock, but then still use the
"pipe_inode_info" afterwards when it does the "__pipe_unlock(pipe)".

This is *very* hard to trigger in practice, since the race window is
very small, and adding debug options seems to just hide it by slowing
things down.

Simon originally reported this way back in July as an Oops in
kmem_cache_allocate due to a single bit corruption (due to the final
"spin_unlock(pipe-&gt;mutex.wait_lock)" incrementing a field in a different
allocation that had re-used the free'd pipe-info), it's taken this long
to figure out.

Since the 'pipe-&gt;files' accesses aren't even protected by the pipe lock
(we very much use the inode lock for that), the simple solution is to
just drop the pipe lock early.  And since there were two users of this
pattern, create a helper function for it.

Introduced commit ba5bb147330a ("pipe: take allocation and freeing of
pipe_inode_info out of -&gt;i_mutex").

Reported-by: Simon Kirby &lt;sim@hostway.ca&gt;
Reported-by: Ian Applegate &lt;ia@cloudflare.com&gt;
Acked-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: stable@kernel.org   # v3.10+
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The pipe code was trying (and failing) to be very careful about freeing
the pipe info only after the last access, with a pattern like:

        spin_lock(&amp;inode-&gt;i_lock);
        if (!--pipe-&gt;files) {
                inode-&gt;i_pipe = NULL;
                kill = 1;
        }
        spin_unlock(&amp;inode-&gt;i_lock);
        __pipe_unlock(pipe);
        if (kill)
                free_pipe_info(pipe);

where the final freeing is done last.

HOWEVER.  The above is actually broken, because while the freeing is
done at the end, if we have two racing processes releasing the pipe
inode info, the one that *doesn't* free it will decrement the -&gt;files
count, and unlock the inode i_lock, but then still use the
"pipe_inode_info" afterwards when it does the "__pipe_unlock(pipe)".

This is *very* hard to trigger in practice, since the race window is
very small, and adding debug options seems to just hide it by slowing
things down.

Simon originally reported this way back in July as an Oops in
kmem_cache_allocate due to a single bit corruption (due to the final
"spin_unlock(pipe-&gt;mutex.wait_lock)" incrementing a field in a different
allocation that had re-used the free'd pipe-info), it's taken this long
to figure out.

Since the 'pipe-&gt;files' accesses aren't even protected by the pipe lock
(we very much use the inode lock for that), the simple solution is to
just drop the pipe lock early.  And since there were two users of this
pattern, create a helper function for it.

Introduced commit ba5bb147330a ("pipe: take allocation and freeing of
pipe_inode_info out of -&gt;i_mutex").

Reported-by: Simon Kirby &lt;sim@hostway.ca&gt;
Reported-by: Ian Applegate &lt;ia@cloudflare.com&gt;
Acked-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: stable@kernel.org   # v3.10+
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
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