linux-stable.git/drivers/block, branch v3.12.20 Linux kernel stable tree floppy: don't write kernel-only members to FDRAWCMD ioctl output 2014-05-15T07:55:49+00:00 Matthew Daley mattd@bugfuzz.com 2014-04-28T07:05:21+00:00 3d43edf5868f260dbfd1353bf243a78f030a08b0 commit 2145e15e0557a01b9195d1c7199a1b92cb9be81f upstream. Do not leak kernel-only floppy_raw_cmd structure members to userspace. This includes the linked-list pointer and the pointer to the allocated DMA space. Signed-off-by: Matthew Daley <mattd@bugfuzz.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 2145e15e0557a01b9195d1c7199a1b92cb9be81f upstream.

Do not leak kernel-only floppy_raw_cmd structure members to userspace.
This includes the linked-list pointer and the pointer to the allocated
DMA space.

Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
floppy: ignore kernel-only members in FDRAWCMD ioctl input 2014-05-15T07:55:48+00:00 Matthew Daley mattd@bugfuzz.com 2014-04-28T07:05:20+00:00 36cdf95db237630373162e20142df4d11efdd543 commit ef87dbe7614341c2e7bfe8d32fcb7028cc97442c upstream. Always clear out these floppy_raw_cmd struct members after copying the entire structure from userspace so that the in-kernel version is always valid and never left in an interdeterminate state. Signed-off-by: Matthew Daley <mattd@bugfuzz.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit ef87dbe7614341c2e7bfe8d32fcb7028cc97442c upstream.

Always clear out these floppy_raw_cmd struct members after copying the
entire structure from userspace so that the in-kernel version is always
valid and never left in an interdeterminate state.

Signed-off-by: Matthew Daley <mattd@bugfuzz.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
mtip32xx: Unmap the DMA segments before completing the IO request 2014-05-15T07:55:35+00:00 Felipe Franciosi felipe@paradoxo.org 2014-03-13T14:34:21+00:00 1fd646cfcd588ca085885963681add522ee90131 commit 368c89d7ac70f937c93cd6f3b65bcfdfb3ba794f upstream. If the buffers are unmapped after completing a request, then stale data might be in the request. Signed-off-by: Felipe Franciosi <felipe@paradoxo.org> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 368c89d7ac70f937c93cd6f3b65bcfdfb3ba794f upstream.

If the buffers are unmapped after completing a request, then stale data
might be in the request.

Signed-off-by: Felipe Franciosi <felipe@paradoxo.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
mtip32xx: Set queue bounce limit 2014-05-15T07:55:34+00:00 Felipe Franciosi felipe@paradoxo.org 2014-03-13T14:34:20+00:00 df50e30db5a55dd3be295f272051424b6c76179d commit 1044b1bb9278f2e656a1a7b63dc24a59506540aa upstream. We need to set the queue bounce limit during the device initialization to prevent excessive bouncing on 32 bit architectures. Signed-off-by: Felipe Franciosi <felipe@paradoxo.org> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 1044b1bb9278f2e656a1a7b63dc24a59506540aa upstream.

We need to set the queue bounce limit during the device initialization to
prevent excessive bouncing on 32 bit architectures.

Signed-off-by: Felipe Franciosi <felipe@paradoxo.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
floppy: bail out in open() if drive is not responding to block0 read 2014-04-18T08:58:54+00:00 Jiri Kosina jkosina@suse.cz 2014-01-10T01:08:13+00:00 e6732e00c9ffc318d21fca56e747f59f85d078a1 commit 7b7b68bba5ef23734c35ffb0d8d82079ed604d33 upstream. In case reading of block 0 during open() fails, it is not the right thing to let open() succeed. Fix this by introducing FD_OPEN_SHOULD_FAIL_BIT flag, and setting it in case the bio callback encounters an error while trying to read block 0. As a bonus, this works around certain broken userspace (blkid), which is not able to properly handle read()s returning IO errors. Hence be nice to those, and bail out during open() already; if block 0 is not readable, read()s are not going to provide any meaningful data anyway. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 7b7b68bba5ef23734c35ffb0d8d82079ed604d33 upstream.

In case reading of block 0 during open() fails, it is not the right thing
to let open() succeed.

Fix this by introducing FD_OPEN_SHOULD_FAIL_BIT flag, and setting it in
case the bio callback encounters an error while trying to read block 0.

As a bonus, this works around certain broken userspace (blkid), which is
not able to properly handle read()s returning IO errors. Hence be nice to
those, and bail out during open() already; if block 0 is not readable,
read()s are not going to provide any meaningful data anyway.

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
mm: close PageTail race 2014-04-03T08:32:30+00:00 David Rientjes rientjes@google.com 2014-03-03T23:38:18+00:00 9a110858ed2e494b8be683c6959113f73685eb1f commit 668f9abbd4334e6c29fa8acd71635c4f9101caa7 upstream. Commit bf6bddf1924e ("mm: introduce compaction and migration for ballooned pages") introduces page_count(page) into memory compaction which dereferences page->first_page if PageTail(page). This results in a very rare NULL pointer dereference on the aforementioned page_count(page). Indeed, anything that does compound_head(), including page_count() is susceptible to racing with prep_compound_page() and seeing a NULL or dangling page->first_page pointer. This patch uses Andrea's implementation of compound_trans_head() that deals with such a race and makes it the default compound_head() implementation. This includes a read memory barrier that ensures that if PageTail(head) is true that we return a head page that is neither NULL nor dangling. The patch then adds a store memory barrier to prep_compound_page() to ensure page->first_page is set. This is the safest way to ensure we see the head page that we are expecting, PageTail(page) is already in the unlikely() path and the memory barriers are unfortunately required. Hugetlbfs is the exception, we don't enforce a store memory barrier during init since no race is possible. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Holger Kiehl <Holger.Kiehl@dwd.de> Cc: Christoph Lameter <cl@linux.com> Cc: Rafael Aquini <aquini@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Mel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz> 
commit 668f9abbd4334e6c29fa8acd71635c4f9101caa7 upstream.

Commit bf6bddf1924e ("mm: introduce compaction and migration for
ballooned pages") introduces page_count(page) into memory compaction
which dereferences page->first_page if PageTail(page).

This results in a very rare NULL pointer dereference on the
aforementioned page_count(page).  Indeed, anything that does
compound_head(), including page_count() is susceptible to racing with
prep_compound_page() and seeing a NULL or dangling page->first_page
pointer.

This patch uses Andrea's implementation of compound_trans_head() that
deals with such a race and makes it the default compound_head()
implementation.  This includes a read memory barrier that ensures that
if PageTail(head) is true that we return a head page that is neither
NULL nor dangling.  The patch then adds a store memory barrier to
prep_compound_page() to ensure page->first_page is set.

This is the safest way to ensure we see the head page that we are
expecting, PageTail(page) is already in the unlikely() path and the
memory barriers are unfortunately required.

Hugetlbfs is the exception, we don't enforce a store memory barrier
during init since no race is possible.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Holger Kiehl <Holger.Kiehl@dwd.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
xen-blkfront: handle backend CLOSED without CLOSING 2014-02-22T21:32:24+00:00 David Vrabel david.vrabel@citrix.com 2014-02-04T18:53:56+00:00 e998c107c0953cced1b8c3ac828c80b5e182cc6c commit 3661371701e714f0cea4120f6a365340858fb4e4 upstream. Backend drivers shouldn't transistion to CLOSED unless the frontend is CLOSED. If a backend does transition to CLOSED too soon then the frontend may not see the CLOSING state and will not properly shutdown. So, treat an unexpected backend CLOSED state the same as CLOSING. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3661371701e714f0cea4120f6a365340858fb4e4 upstream.

Backend drivers shouldn't transistion to CLOSED unless the frontend is
CLOSED.  If a backend does transition to CLOSED too soon then the
frontend may not see the CLOSING state and will not properly shutdown.

So, treat an unexpected backend CLOSED state the same as CLOSING.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xen/pvhvm: If xen_platform_pci=0 is set don't blow up (v4). 2014-02-13T21:50:10+00:00 Konrad Rzeszutek Wilk konrad.wilk@oracle.com 2013-11-26T20:05:40+00:00 d7c80b2d79624efd8fb6c2bfb44bd41ea2831cd4 commit 51c71a3bbaca868043cc45b3ad3786dd48a90235 upstream. The user has the option of disabling the platform driver: 00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 01) which is used to unplug the emulated drivers (IDE, Realtek 8169, etc) and allow the PV drivers to take over. If the user wishes to disable that they can set: xen_platform_pci=0 (in the guest config file) or xen_emul_unplug=never (on the Linux command line) except it does not work properly. The PV drivers still try to load and since the Xen platform driver is not run - and it has not initialized the grant tables, most of the PV drivers stumble upon: input: Xen Virtual Keyboard as /devices/virtual/input/input5 input: Xen Virtual Pointer as /devices/virtual/input/input6M ------------[ cut here ]------------ kernel BUG at /home/konrad/ssd/konrad/linux/drivers/xen/grant-table.c:1206! invalid opcode: 0000 [#1] SMP Modules linked in: xen_kbdfront(+) xenfs xen_privcmd CPU: 6 PID: 1389 Comm: modprobe Not tainted 3.13.0-rc1upstream-00021-ga6c892b-dirty #1 Hardware name: Xen HVM domU, BIOS 4.4-unstable 11/26/2013 RIP: 0010:[<ffffffff813ddc40>] [<ffffffff813ddc40>] get_free_entries+0x2e0/0x300 Call Trace: [<ffffffff8150d9a3>] ? evdev_connect+0x1e3/0x240 [<ffffffff813ddd0e>] gnttab_grant_foreign_access+0x2e/0x70 [<ffffffffa0010081>] xenkbd_connect_backend+0x41/0x290 [xen_kbdfront] [<ffffffffa0010a12>] xenkbd_probe+0x2f2/0x324 [xen_kbdfront] [<ffffffff813e5757>] xenbus_dev_probe+0x77/0x130 [<ffffffff813e7217>] xenbus_frontend_dev_probe+0x47/0x50 [<ffffffff8145e9a9>] driver_probe_device+0x89/0x230 [<ffffffff8145ebeb>] __driver_attach+0x9b/0xa0 [<ffffffff8145eb50>] ? driver_probe_device+0x230/0x230 [<ffffffff8145eb50>] ? driver_probe_device+0x230/0x230 [<ffffffff8145cf1c>] bus_for_each_dev+0x8c/0xb0 [<ffffffff8145e7d9>] driver_attach+0x19/0x20 [<ffffffff8145e260>] bus_add_driver+0x1a0/0x220 [<ffffffff8145f1ff>] driver_register+0x5f/0xf0 [<ffffffff813e55c5>] xenbus_register_driver_common+0x15/0x20 [<ffffffff813e76b3>] xenbus_register_frontend+0x23/0x40 [<ffffffffa0015000>] ? 0xffffffffa0014fff [<ffffffffa001502b>] xenkbd_init+0x2b/0x1000 [xen_kbdfront] [<ffffffff81002049>] do_one_initcall+0x49/0x170 .. snip.. which is hardly nice. This patch fixes this by having each PV driver check for: - if running in PV, then it is fine to execute (as that is their native environment). - if running in HVM, check if user wanted 'xen_emul_unplug=never', in which case bail out and don't load any PV drivers. - if running in HVM, and if PCI device 5853:0001 (xen_platform_pci) does not exist, then bail out and not load PV drivers. - (v2) if running in HVM, and if the user wanted 'xen_emul_unplug=ide-disks', then bail out for all PV devices _except_ the block one. Ditto for the network one ('nics'). - (v2) if running in HVM, and if the user wanted 'xen_emul_unplug=unnecessary' then load block PV driver, and also setup the legacy IDE paths. In (v3) make it actually load PV drivers. Reported-by: Sander Eikelenboom <linux@eikelenboom.it Reported-by: Anthony PERARD <anthony.perard@citrix.com> Reported-and-Tested-by: Fabio Fantoni <fabio.fantoni@m2r.biz> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [v2: Add extra logic to handle the myrid ways 'xen_emul_unplug' can be used per Ian and Stefano suggestion] [v3: Make the unnecessary case work properly] [v4: s/disks/ide-disks/ spotted by Fabio] Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> [for PCI parts] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 51c71a3bbaca868043cc45b3ad3786dd48a90235 upstream.

The user has the option of disabling the platform driver:
00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 01)

which is used to unplug the emulated drivers (IDE, Realtek 8169, etc)
and allow the PV drivers to take over. If the user wishes
to disable that they can set:

  xen_platform_pci=0
  (in the guest config file)

or
  xen_emul_unplug=never
  (on the Linux command line)

except it does not work properly. The PV drivers still try to
load and since the Xen platform driver is not run - and it
has not initialized the grant tables, most of the PV drivers
stumble upon:

input: Xen Virtual Keyboard as /devices/virtual/input/input5
input: Xen Virtual Pointer as /devices/virtual/input/input6M
------------[ cut here ]------------
kernel BUG at /home/konrad/ssd/konrad/linux/drivers/xen/grant-table.c:1206!
invalid opcode: 0000 [#1] SMP
Modules linked in: xen_kbdfront(+) xenfs xen_privcmd
CPU: 6 PID: 1389 Comm: modprobe Not tainted 3.13.0-rc1upstream-00021-ga6c892b-dirty #1
Hardware name: Xen HVM domU, BIOS 4.4-unstable 11/26/2013
RIP: 0010:[<ffffffff813ddc40>]  [<ffffffff813ddc40>] get_free_entries+0x2e0/0x300
Call Trace:
 [<ffffffff8150d9a3>] ? evdev_connect+0x1e3/0x240
 [<ffffffff813ddd0e>] gnttab_grant_foreign_access+0x2e/0x70
 [<ffffffffa0010081>] xenkbd_connect_backend+0x41/0x290 [xen_kbdfront]
 [<ffffffffa0010a12>] xenkbd_probe+0x2f2/0x324 [xen_kbdfront]
 [<ffffffff813e5757>] xenbus_dev_probe+0x77/0x130
 [<ffffffff813e7217>] xenbus_frontend_dev_probe+0x47/0x50
 [<ffffffff8145e9a9>] driver_probe_device+0x89/0x230
 [<ffffffff8145ebeb>] __driver_attach+0x9b/0xa0
 [<ffffffff8145eb50>] ? driver_probe_device+0x230/0x230
 [<ffffffff8145eb50>] ? driver_probe_device+0x230/0x230
 [<ffffffff8145cf1c>] bus_for_each_dev+0x8c/0xb0
 [<ffffffff8145e7d9>] driver_attach+0x19/0x20
 [<ffffffff8145e260>] bus_add_driver+0x1a0/0x220
 [<ffffffff8145f1ff>] driver_register+0x5f/0xf0
 [<ffffffff813e55c5>] xenbus_register_driver_common+0x15/0x20
 [<ffffffff813e76b3>] xenbus_register_frontend+0x23/0x40
 [<ffffffffa0015000>] ? 0xffffffffa0014fff
 [<ffffffffa001502b>] xenkbd_init+0x2b/0x1000 [xen_kbdfront]
 [<ffffffff81002049>] do_one_initcall+0x49/0x170

.. snip..

which is hardly nice. This patch fixes this by having each
PV driver check for:
 - if running in PV, then it is fine to execute (as that is their
   native environment).
 - if running in HVM, check if user wanted 'xen_emul_unplug=never',
   in which case bail out and don't load any PV drivers.
 - if running in HVM, and if PCI device 5853:0001 (xen_platform_pci)
   does not exist, then bail out and not load PV drivers.
 - (v2) if running in HVM, and if the user wanted 'xen_emul_unplug=ide-disks',
   then bail out for all PV devices _except_ the block one.
   Ditto for the network one ('nics').
 - (v2) if running in HVM, and if the user wanted 'xen_emul_unplug=unnecessary'
   then load block PV driver, and also setup the legacy IDE paths.
   In (v3) make it actually load PV drivers.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it
Reported-by: Anthony PERARD <anthony.perard@citrix.com>
Reported-and-Tested-by: Fabio Fantoni <fabio.fantoni@m2r.biz>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v2: Add extra logic to handle the myrid ways 'xen_emul_unplug'
can be used per Ian and Stefano suggestion]
[v3: Make the unnecessary case work properly]
[v4: s/disks/ide-disks/ spotted by Fabio]
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com> [for PCI parts]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
xen/blkback: fix reference counting 2013-12-04T19:05:25+00:00 Vegard Nossum vegard.nossum@oracle.com 2013-09-05T11:00:14+00:00 27c3c8635222fbaea7bdc3a7fb3c40832106a840 commit ea5ec76d76da9279d12027c1828544c5ccbe7932 upstream. If the permission check fails, we drop a reference to the blkif without having taken it in the first place. The bug was introduced in commit 604c499cbbcc3d5fe5fb8d53306aa0fae1990109 (xen/blkback: Check device permissions before allowing OP_DISCARD). Cc: Jan Beulich <JBeulich@suse.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ea5ec76d76da9279d12027c1828544c5ccbe7932 upstream.

If the permission check fails, we drop a reference to the blkif without
having taken it in the first place. The bug was introduced in commit
604c499cbbcc3d5fe5fb8d53306aa0fae1990109 (xen/blkback: Check device
permissions before allowing OP_DISCARD).

Cc: Jan Beulich <JBeulich@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
loop: fix crash when using unassigned loop device 2013-12-04T19:05:24+00:00 Mikulas Patocka mpatocka@redhat.com 2013-10-15T20:14:38+00:00 b9762e28e9f03a72e80e4923d980ba4daabe8a86 commit ef7e7c82e02b602f29c2b87f42dcd6143a6777da upstream. When the loop module is loaded, it creates 8 loop devices /dev/loop[0-7]. The devices have no request routine and thus, when they are used without being assigned, a crash happens. For example, these commands cause crash (assuming there are no used loop devices): Kernel Fault: Code=26 regs=000000007f420980 (Addr=0000000000000010) CPU: 1 PID: 50 Comm: kworker/1:1 Not tainted 3.11.0 #1 Workqueue: ksnaphd do_metadata [dm_snapshot] task: 000000007fcf4078 ti: 000000007f420000 task.ti: 000000007f420000 [ 116.319988] YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI PSW: 00001000000001001111111100001111 Not tainted r00-03 000000ff0804ff0f 00000000408bf5d0 00000000402d8204 000000007b7ff6c0 r04-07 00000000408a95d0 000000007f420950 000000007b7ff6c0 000000007d06c930 r08-11 000000007f4205c0 0000000000000001 000000007f4205c0 000000007f4204b8 r12-15 0000000000000010 0000000000000000 0000000000000000 0000000000000000 r16-19 000000001108dd48 000000004061cd7c 000000007d859800 000000000800000f r20-23 0000000000000000 0000000000000008 0000000000000000 0000000000000000 r24-27 00000000ffffffff 000000007b7ff6c0 000000007d859800 00000000408a95d0 r28-31 0000000000000000 000000007f420950 000000007f420980 000000007f4208e8 sr00-03 0000000000000000 0000000000000000 0000000000000000 0000000000303000 sr04-07 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 117.549988] IASQ: 0000000000000000 0000000000000000 IAOQ: 00000000402d82fc 00000000402d8300 IIR: 53820020 ISR: 0000000000000000 IOR: 0000000000000010 CPU: 1 CR30: 000000007f420000 CR31: ffffffffffffffff ORIG_R28: 0000000000000001 IAOQ[0]: generic_make_request+0x11c/0x1a0 IAOQ[1]: generic_make_request+0x120/0x1a0 RP(r2): generic_make_request+0x24/0x1a0 Backtrace: [<00000000402d83f0>] submit_bio+0x70/0x140 [<0000000011087c4c>] dispatch_io+0x234/0x478 [dm_mod] [<0000000011087f44>] sync_io+0xb4/0x190 [dm_mod] [<00000000110883bc>] dm_io+0x2c4/0x310 [dm_mod] [<00000000110bfcd0>] do_metadata+0x28/0xb0 [dm_snapshot] [<00000000401591d8>] process_one_work+0x160/0x460 [<0000000040159bc0>] worker_thread+0x300/0x478 [<0000000040161a70>] kthread+0x118/0x128 [<0000000040104020>] end_fault_vector+0x20/0x28 [<0000000040177220>] task_tick_fair+0x420/0x4d0 [<00000000401aa048>] invoke_rcu_core+0x50/0x60 [<00000000401ad5b8>] rcu_check_callbacks+0x210/0x8d8 [<000000004014aaa0>] update_process_times+0xa8/0xc0 [<00000000401ab86c>] rcu_process_callbacks+0x4b4/0x598 [<0000000040142408>] __do_softirq+0x250/0x2c0 [<00000000401789d0>] find_busiest_group+0x3c0/0xc70 [ 119.379988] Kernel panic - not syncing: Kernel Fault Rebooting in 1 seconds.. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ef7e7c82e02b602f29c2b87f42dcd6143a6777da upstream.

When the loop module is loaded, it creates 8 loop devices /dev/loop[0-7].
The devices have no request routine and thus, when they are used without
being assigned, a crash happens.

For example, these commands cause crash (assuming there are no used loop
devices):

Kernel Fault: Code=26 regs=000000007f420980 (Addr=0000000000000010)
CPU: 1 PID: 50 Comm: kworker/1:1 Not tainted 3.11.0 #1
Workqueue: ksnaphd do_metadata [dm_snapshot]
task: 000000007fcf4078 ti: 000000007f420000 task.ti: 000000007f420000
[  116.319988]
     YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
PSW: 00001000000001001111111100001111 Not tainted
r00-03  000000ff0804ff0f 00000000408bf5d0 00000000402d8204 000000007b7ff6c0
r04-07  00000000408a95d0 000000007f420950 000000007b7ff6c0 000000007d06c930
r08-11  000000007f4205c0 0000000000000001 000000007f4205c0 000000007f4204b8
r12-15  0000000000000010 0000000000000000 0000000000000000 0000000000000000
r16-19  000000001108dd48 000000004061cd7c 000000007d859800 000000000800000f
r20-23  0000000000000000 0000000000000008 0000000000000000 0000000000000000
r24-27  00000000ffffffff 000000007b7ff6c0 000000007d859800 00000000408a95d0
r28-31  0000000000000000 000000007f420950 000000007f420980 000000007f4208e8
sr00-03  0000000000000000 0000000000000000 0000000000000000 0000000000303000
sr04-07  0000000000000000 0000000000000000 0000000000000000 0000000000000000
[  117.549988]
IASQ: 0000000000000000 0000000000000000 IAOQ: 00000000402d82fc 00000000402d8300
 IIR: 53820020    ISR: 0000000000000000  IOR: 0000000000000010
 CPU:        1   CR30: 000000007f420000 CR31: ffffffffffffffff
 ORIG_R28: 0000000000000001
 IAOQ[0]: generic_make_request+0x11c/0x1a0
 IAOQ[1]: generic_make_request+0x120/0x1a0
 RP(r2): generic_make_request+0x24/0x1a0
Backtrace:
 [<00000000402d83f0>] submit_bio+0x70/0x140
 [<0000000011087c4c>] dispatch_io+0x234/0x478 [dm_mod]
 [<0000000011087f44>] sync_io+0xb4/0x190 [dm_mod]
 [<00000000110883bc>] dm_io+0x2c4/0x310 [dm_mod]
 [<00000000110bfcd0>] do_metadata+0x28/0xb0 [dm_snapshot]
 [<00000000401591d8>] process_one_work+0x160/0x460
 [<0000000040159bc0>] worker_thread+0x300/0x478
 [<0000000040161a70>] kthread+0x118/0x128
 [<0000000040104020>] end_fault_vector+0x20/0x28
 [<0000000040177220>] task_tick_fair+0x420/0x4d0
 [<00000000401aa048>] invoke_rcu_core+0x50/0x60
 [<00000000401ad5b8>] rcu_check_callbacks+0x210/0x8d8
 [<000000004014aaa0>] update_process_times+0xa8/0xc0
 [<00000000401ab86c>] rcu_process_callbacks+0x4b4/0x598
 [<0000000040142408>] __do_softirq+0x250/0x2c0
 [<00000000401789d0>] find_busiest_group+0x3c0/0xc70
[  119.379988]
Kernel panic - not syncing: Kernel Fault
Rebooting in 1 seconds..

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>