LinuxLists.cc - virt_blk BUG: sleeping function called from invalid context

2014-06-27 11:57:41

Subject: virt_blk BUG: sleeping function called from invalid context

Hi All,

We've had a report[1] of the virt_blk driver causing a lot of spew
because it's calling a sleeping function from an invalid context. The
backtrace is below. This is with kernel v3.16-rc2-69-gd91d66e88ea9.

The reporter is on CC and can give you relevant details.

josh

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1113805

[drm] Initialized bochs-drm 1.0.0 20130925 for 0000:00:02.0 on minor 0
virtio-pci 0000:00:05.0: irq 40 for MSI/MSI-X
virtio-pci 0000:00:05.0: irq 41 for MSI/MSI-X
vda: vda1 vda2
virtio-pci 0000:00:06.0: irq 42 for MSI/MSI-X
virtio-pci 0000:00:06.0: irq 43 for MSI/MSI-X
vdb: vdb1
tsc: Refined TSC clocksource calibration: 3392.169 MHz
md: bind<vdb1>
mdadm (350) used greatest stack depth: 12384 bytes left
md: bind<vda2>
md: raid1 personality registered for level 1
md/raid1:md127: active with 2 out of 2 mirrors
created bitmap (1 pages) for device md127
md127: bitmap initialized from disk: read 1 pages, set 0 of 153 bits
md127: detected capacity change from 0 to 10203693056
md127: unknown partition table
systemd-cryptsetup[358]: Set cipher aes, mode xts-plain64, key size
512 bits for device
/dev/disk/by-uuid/6972a564-542d-498b-b3a0-7d71c2e966a2.
md127: unknown partition table
md127: unknown partition table
dracut-initqueue[296]: Scanning devices dm-0 for LVM logical volumes
fedora-foo1/root fedora-foo1/swap fedora-foo1/root fedora-foo1/swap
dracut-initqueue[296]: inactive '/dev/fedora-foo1/root' [7.42 GiB] inherit
dracut-initqueue[296]: inactive '/dev/fedora-foo1/swap' [2.00 GiB] inherit
systemd-fsck[662]: /dev/mapper/fedora--foo1-root: clean, 22215/486720
files, 222526/1944576 blocks
BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:586
in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
2 locks held by swapper/1/0:
#0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>]
virtblk_done+0x42/0xe0 [virtio_blk]
#1: (&(&bitmap->counts.lock)->rlock){-.....}, at:
[<ffffffff81633718>] bitmap_endwrite+0x68/0x240
irq event stamp: 33518
hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230
hardirqs last disabled at (33516): [<ffffffff818122ed>]
common_interrupt+0x6d/0x72
softirqs last enabled at (33518): [<ffffffff810a1272>]
_local_bh_enable+0x22/0x50
softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
0000000000000000 f90db13964f4ee05 ffff88007d403b80 ffffffff81807b4c
0000000000000000 ffff88007d403ba8 ffffffff810d4f14 0000000000000000
0000000000441800 ffff880078fa1780 ffff88007d403c38 ffffffff8180caf2
Call Trace:
<IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66
[<ffffffff810d4f14>] __might_sleep+0x184/0x240
[<ffffffff8180caf2>] mutex_lock_nested+0x42/0x440
[<ffffffff810e1de6>] ? local_clock+0x16/0x30
[<ffffffff810fc23f>] ? lock_release_holdtime.part.28+0xf/0x200
[<ffffffff812d76a0>] kernfs_notify+0x90/0x150
[<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240
[<ffffffffa00de863>] close_write+0x93/0xb0 [raid1]
[<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1]
[<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1]
[<ffffffff813acb8b>] bio_endio+0x6b/0xa0
[<ffffffff813b46c4>] blk_update_request+0x94/0x420
[<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70
[<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk]
[<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120
[<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30
[<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk]
[<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring]
[<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340
[<ffffffff8111647d>] handle_irq_event+0x3d/0x60
[<ffffffff81119436>] handle_edge_irq+0x66/0x130
[<ffffffff8101c3e4>] handle_irq+0x84/0x150
[<ffffffff818146ad>] do_IRQ+0x4d/0xe0
[<ffffffff818122f2>] common_interrupt+0x72/0x72
<EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10
[<ffffffff81025454>] default_idle+0x24/0x230
[<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20
[<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0
[<ffffffff8104df1b>] start_secondary+0x25b/0x300

=================================
[ INFO: inconsistent lock state ]
3.16.0-0.rc2.git2.1.fc21.x86_64 #1 Not tainted
---------------------------------
inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
swapper/1/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
(kernfs_mutex){?.+.+.}, at: [<ffffffff812d76a0>] kernfs_notify+0x90/0x150
{HARDIRQ-ON-W} state was registered at:
[<ffffffff811004b2>] __lock_acquire+0x942/0x1ca0
[<ffffffff811020f4>] lock_acquire+0xa4/0x1d0
[<ffffffff8180cb35>] mutex_lock_nested+0x85/0x440
[<ffffffff812d6d6f>] kernfs_activate+0x1f/0xf0
[<ffffffff812d7140>] kernfs_create_root+0xf0/0x110
[<ffffffff821f1ddc>] sysfs_init+0x13/0x51
[<ffffffff821ef5af>] mnt_init+0x107/0x231
[<ffffffff821ef213>] vfs_caches_init+0x98/0x106
[<ffffffff821bdfb0>] start_kernel+0x44f/0x4bc
[<ffffffff821bd4d7>] x86_64_start_reservations+0x2a/0x2c
[<ffffffff821bd626>] x86_64_start_kernel+0x14d/0x170
irq event stamp: 33518
hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230
hardirqs last disabled at (33516): [<ffffffff818122ed>]
common_interrupt+0x6d/0x72
softirqs last enabled at (33518): [<ffffffff810a1272>]
_local_bh_enable+0x22/0x50
softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80

other info that might
help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(kernfs_mutex);
<Interrupt>
lock(kernfs_mutex);

*** DEADLOCK ***
2 locks held by swapper/1/0:
#0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>]
virtblk_done+0x42/0xe0 [virtio_blk]
#1: (&(&bitmap->counts.lock)->rlock){-.....}, at:
[<ffffffff81633718>] bitmap_endwrite+0x68/0x240

stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
0000000000000000 f90db13964f4ee05 ffff88007d4039d0 ffffffff81807b4c
ffff88007bcb19d0 ffff88007d403a20 ffffffff81805358 0000000000000000
0000000000000000 0000000000000001 ffff88007bcb25a8 ffff88007bcb19d0
Call Trace:
<IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66
[<ffffffff81805358>] print_usage_bug+0x1f0/0x205
[<ffffffff810ff450>] mark_lock+0x610/0x6d0
[<ffffffff810fe520>] ? print_shortest_lock_dependencies+0x1d0/0x1d0
[<ffffffff81100614>] __lock_acquire+0xaa4/0x1ca0
[<ffffffff8101dc4d>] ? show_trace_log_lvl+0x4d/0x60
[<ffffffff8101c8ad>] ? show_stack_log_lvl+0xad/0x1b0
[<ffffffff811020f4>] lock_acquire+0xa4/0x1d0
[<ffffffff812d76a0>] ? kernfs_notify+0x90/0x150
[<ffffffff8180cb35>] mutex_lock_nested+0x85/0x440
[<ffffffff812d76a0>] ? kernfs_notify+0x90/0x150
[<ffffffff810fc23f>] ? lock_release_holdtime.part.28+0xf/0x200
[<ffffffff812d76a0>] ? kernfs_notify+0x90/0x150
[<ffffffff812d76a0>] kernfs_notify+0x90/0x150
[<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240
[<ffffffffa00de863>] close_write+0x93/0xb0 [raid1]
[<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1]
[<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1]
[<ffffffff813acb8b>] bio_endio+0x6b/0xa0
[<ffffffff813b46c4>] blk_update_request+0x94/0x420
[<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70
[<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk]
[<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120
[<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30
[<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk]
[<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring]
[<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340
[<ffffffff8111647d>] handle_irq_event+0x3d/0x60
[<ffffffff81119436>] handle_edge_irq+0x66/0x130
[<ffffffff8101c3e4>] handle_irq+0x84/0x150
[<ffffffff818146ad>] do_IRQ+0x4d/0xe0
[<ffffffff818122f2>] common_interrupt+0x72/0x72
<EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10
[<ffffffff81025454>] default_idle+0x24/0x230
[<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20
[<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0
[<ffffffff8104df1b>] start_secondary+0x25b/0x30

2014-06-29 08:26:27

by Michael S. Tsirkin

[permalink] [raw]

Subject: Re: virt_blk BUG: sleeping function called from invalid context

On Fri, Jun 27, 2014 at 07:57:38AM -0400, Josh Boyer wrote:
> Hi All,
>
> We've had a report[1] of the virt_blk driver causing a lot of spew
> because it's calling a sleeping function from an invalid context. The
> backtrace is below. This is with kernel v3.16-rc2-69-gd91d66e88ea9.

Hi Jens, pls see below - it looks like the call to blk_mq_end_io
from IRQ context is causing the issue.
IIUC you switched virtio to this from __blk_end_request_all in

commit 1cf7e9c68fe84248174e998922b39e508375e7c1
virtio_blk: blk-mq support

Is this always safe?
I note that at least one other driver is doing this:
drivers/block/mtip32xx/mtip32xx.c

Thanks!

> The reporter is on CC and can give you relevant details.
>
> josh
>
> [1] https://bugzilla.redhat.com/show_bug.cgi?id=1113805
>
> [drm] Initialized bochs-drm 1.0.0 20130925 for 0000:00:02.0 on minor 0
> virtio-pci 0000:00:05.0: irq 40 for MSI/MSI-X
> virtio-pci 0000:00:05.0: irq 41 for MSI/MSI-X
> vda: vda1 vda2
> virtio-pci 0000:00:06.0: irq 42 for MSI/MSI-X
> virtio-pci 0000:00:06.0: irq 43 for MSI/MSI-X
> vdb: vdb1
> tsc: Refined TSC clocksource calibration: 3392.169 MHz
> md: bind<vdb1>
> mdadm (350) used greatest stack depth: 12384 bytes left
> md: bind<vda2>
> md: raid1 personality registered for level 1
> md/raid1:md127: active with 2 out of 2 mirrors
> created bitmap (1 pages) for device md127
> md127: bitmap initialized from disk: read 1 pages, set 0 of 153 bits
> md127: detected capacity change from 0 to 10203693056
> md127: unknown partition table
> systemd-cryptsetup[358]: Set cipher aes, mode xts-plain64, key size
> 512 bits for device
> /dev/disk/by-uuid/6972a564-542d-498b-b3a0-7d71c2e966a2.
> md127: unknown partition table
> md127: unknown partition table
> dracut-initqueue[296]: Scanning devices dm-0 for LVM logical volumes
> fedora-foo1/root fedora-foo1/swap fedora-foo1/root fedora-foo1/swap
> dracut-initqueue[296]: inactive '/dev/fedora-foo1/root' [7.42 GiB] inherit
> dracut-initqueue[296]: inactive '/dev/fedora-foo1/swap' [2.00 GiB] inherit
> systemd-fsck[662]: /dev/mapper/fedora--foo1-root: clean, 22215/486720
> files, 222526/1944576 blocks
> BUG: sleeping function called from invalid context at
> kernel/locking/mutex.c:586
> in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
> 2 locks held by swapper/1/0:
> #0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>]
> virtblk_done+0x42/0xe0 [virtio_blk]
> #1: (&(&bitmap->counts.lock)->rlock){-.....}, at:
> [<ffffffff81633718>] bitmap_endwrite+0x68/0x240
> irq event stamp: 33518
> hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230
> hardirqs last disabled at (33516): [<ffffffff818122ed>]
> common_interrupt+0x6d/0x72
> softirqs last enabled at (33518): [<ffffffff810a1272>]
> _local_bh_enable+0x22/0x50
> softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> 0000000000000000 f90db13964f4ee05 ffff88007d403b80 ffffffff81807b4c
> 0000000000000000 ffff88007d403ba8 ffffffff810d4f14 0000000000000000
> 0000000000441800 ffff880078fa1780 ffff88007d403c38 ffffffff8180caf2
> Call Trace:
> <IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66
> [<ffffffff810d4f14>] __might_sleep+0x184/0x240
> [<ffffffff8180caf2>] mutex_lock_nested+0x42/0x440
> [<ffffffff810e1de6>] ? local_clock+0x16/0x30
> [<ffffffff810fc23f>] ? lock_release_holdtime.part.28+0xf/0x200
> [<ffffffff812d76a0>] kernfs_notify+0x90/0x150
> [<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240
> [<ffffffffa00de863>] close_write+0x93/0xb0 [raid1]
> [<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1]
> [<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1]
> [<ffffffff813acb8b>] bio_endio+0x6b/0xa0
> [<ffffffff813b46c4>] blk_update_request+0x94/0x420
> [<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70
> [<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk]
> [<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120
> [<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30
> [<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk]
> [<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring]
> [<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340
> [<ffffffff8111647d>] handle_irq_event+0x3d/0x60
> [<ffffffff81119436>] handle_edge_irq+0x66/0x130
> [<ffffffff8101c3e4>] handle_irq+0x84/0x150
> [<ffffffff818146ad>] do_IRQ+0x4d/0xe0
> [<ffffffff818122f2>] common_interrupt+0x72/0x72
> <EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10
> [<ffffffff81025454>] default_idle+0x24/0x230
> [<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20
> [<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0
> [<ffffffff8104df1b>] start_secondary+0x25b/0x300
>
> =================================
> [ INFO: inconsistent lock state ]
> 3.16.0-0.rc2.git2.1.fc21.x86_64 #1 Not tainted
> ---------------------------------
> inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage.
> swapper/1/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
> (kernfs_mutex){?.+.+.}, at: [<ffffffff812d76a0>] kernfs_notify+0x90/0x150
> {HARDIRQ-ON-W} state was registered at:
> [<ffffffff811004b2>] __lock_acquire+0x942/0x1ca0
> [<ffffffff811020f4>] lock_acquire+0xa4/0x1d0
> [<ffffffff8180cb35>] mutex_lock_nested+0x85/0x440
> [<ffffffff812d6d6f>] kernfs_activate+0x1f/0xf0
> [<ffffffff812d7140>] kernfs_create_root+0xf0/0x110
> [<ffffffff821f1ddc>] sysfs_init+0x13/0x51
> [<ffffffff821ef5af>] mnt_init+0x107/0x231
> [<ffffffff821ef213>] vfs_caches_init+0x98/0x106
> [<ffffffff821bdfb0>] start_kernel+0x44f/0x4bc
> [<ffffffff821bd4d7>] x86_64_start_reservations+0x2a/0x2c
> [<ffffffff821bd626>] x86_64_start_kernel+0x14d/0x170
> irq event stamp: 33518
> hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230
> hardirqs last disabled at (33516): [<ffffffff818122ed>]
> common_interrupt+0x6d/0x72
> softirqs last enabled at (33518): [<ffffffff810a1272>]
> _local_bh_enable+0x22/0x50
> softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80
>
> other info that might
> help us debug this:
> Possible unsafe locking scenario:
> CPU0
> ----
> lock(kernfs_mutex);
> <Interrupt>
> lock(kernfs_mutex);
>
> *** DEADLOCK ***
> 2 locks held by swapper/1/0:
> #0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>]
> virtblk_done+0x42/0xe0 [virtio_blk]
> #1: (&(&bitmap->counts.lock)->rlock){-.....}, at:
> [<ffffffff81633718>] bitmap_endwrite+0x68/0x240
>
> stack backtrace:
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> 0000000000000000 f90db13964f4ee05 ffff88007d4039d0 ffffffff81807b4c
> ffff88007bcb19d0 ffff88007d403a20 ffffffff81805358 0000000000000000
> 0000000000000000 0000000000000001 ffff88007bcb25a8 ffff88007bcb19d0
> Call Trace:
> <IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66
> [<ffffffff81805358>] print_usage_bug+0x1f0/0x205
> [<ffffffff810ff450>] mark_lock+0x610/0x6d0
> [<ffffffff810fe520>] ? print_shortest_lock_dependencies+0x1d0/0x1d0
> [<ffffffff81100614>] __lock_acquire+0xaa4/0x1ca0
> [<ffffffff8101dc4d>] ? show_trace_log_lvl+0x4d/0x60
> [<ffffffff8101c8ad>] ? show_stack_log_lvl+0xad/0x1b0
> [<ffffffff811020f4>] lock_acquire+0xa4/0x1d0
> [<ffffffff812d76a0>] ? kernfs_notify+0x90/0x150
> [<ffffffff8180cb35>] mutex_lock_nested+0x85/0x440
> [<ffffffff812d76a0>] ? kernfs_notify+0x90/0x150
> [<ffffffff810fc23f>] ? lock_release_holdtime.part.28+0xf/0x200
> [<ffffffff812d76a0>] ? kernfs_notify+0x90/0x150
> [<ffffffff812d76a0>] kernfs_notify+0x90/0x150
> [<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240
> [<ffffffffa00de863>] close_write+0x93/0xb0 [raid1]
> [<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1]
> [<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1]
> [<ffffffff813acb8b>] bio_endio+0x6b/0xa0
> [<ffffffff813b46c4>] blk_update_request+0x94/0x420
> [<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70
> [<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk]
> [<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120
> [<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30
> [<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk]
> [<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring]
> [<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340
> [<ffffffff8111647d>] handle_irq_event+0x3d/0x60
> [<ffffffff81119436>] handle_edge_irq+0x66/0x130
> [<ffffffff8101c3e4>] handle_irq+0x84/0x150
> [<ffffffff818146ad>] do_IRQ+0x4d/0xe0
> [<ffffffff818122f2>] common_interrupt+0x72/0x72
> <EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10
> [<ffffffff81025454>] default_idle+0x24/0x230
> [<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20
> [<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0
> [<ffffffff8104df1b>] start_secondary+0x25b/0x30

2014-06-29 19:32:28

by Christoph Hellwig

[permalink] [raw]

Subject: Re: virt_blk BUG: sleeping function called from invalid context

On Sun, Jun 29, 2014 at 11:26:37AM +0300, Michael S. Tsirkin wrote:
> On Fri, Jun 27, 2014 at 07:57:38AM -0400, Josh Boyer wrote:
> > Hi All,
> >
> > We've had a report[1] of the virt_blk driver causing a lot of spew
> > because it's calling a sleeping function from an invalid context. The
> > backtrace is below. This is with kernel v3.16-rc2-69-gd91d66e88ea9.
>
> Hi Jens, pls see below - it looks like the call to blk_mq_end_io
> from IRQ context is causing the issue.
> IIUC you switched virtio to this from __blk_end_request_all in
>
> commit 1cf7e9c68fe84248174e998922b39e508375e7c1
> virtio_blk: blk-mq support
>
> Is this always safe?
> I note that at least one other driver is doing this:
> drivers/block/mtip32xx/mtip32xx.c

Just like __blk_end_request_all blk_mq_end_io is supposed to be called
from irq context. The problem is that the MD bio end_io handler is calling
a sleeping function. Not sure if that's a bug in MD though given the
kernfs symbols in the all trace and the recent churn in that area.

2014-06-29 20:47:07

by Michael S. Tsirkin

[permalink] [raw]

Subject: Re: virt_blk BUG: sleeping function called from invalid context

On Sun, Jun 29, 2014 at 09:32:22PM +0200, Christoph Hellwig wrote:
> On Sun, Jun 29, 2014 at 11:26:37AM +0300, Michael S. Tsirkin wrote:
> > On Fri, Jun 27, 2014 at 07:57:38AM -0400, Josh Boyer wrote:
> > > Hi All,
> > >
> > > We've had a report[1] of the virt_blk driver causing a lot of spew
> > > because it's calling a sleeping function from an invalid context. The
> > > backtrace is below. This is with kernel v3.16-rc2-69-gd91d66e88ea9.
> >
> > Hi Jens, pls see below - it looks like the call to blk_mq_end_io
> > from IRQ context is causing the issue.
> > IIUC you switched virtio to this from __blk_end_request_all in
> >
> > commit 1cf7e9c68fe84248174e998922b39e508375e7c1
> > virtio_blk: blk-mq support
> >
> > Is this always safe?
> > I note that at least one other driver is doing this:
> > drivers/block/mtip32xx/mtip32xx.c
>
> Just like __blk_end_request_all blk_mq_end_io is supposed to be called
> from irq context. The problem is that the MD bio end_io handler is calling
> a sleeping function. Not sure if that's a bug in MD though given the
> kernfs symbols in the all trace and the recent churn in that area.

My understanding is this:

bitmap_endwrite -> calls sysfs_notify_dirent_safe under spinlock
-> calls kernfs_notify which takes a mutex.

So I am guessing it is this commit:

commit d911d98748018f7c8facc035ba39c30f5cce6f9c
Author: Tejun Heo <[email protected]>
Date: Wed Apr 9 11:07:31 2014 -0400

kernfs: make kernfs_notify() trigger inotify events too

Tejun, what do you think?

Josh, Brian, could you try reverting that commit to see if it helps?

--
MST

2014-06-29 20:55:25

by Jens Axboe

[permalink] [raw]

Subject: Re: virt_blk BUG: sleeping function called from invalid context

On 06/29/2014 02:47 PM, Michael S. Tsirkin wrote:
> On Sun, Jun 29, 2014 at 09:32:22PM +0200, Christoph Hellwig wrote:
>> On Sun, Jun 29, 2014 at 11:26:37AM +0300, Michael S. Tsirkin wrote:
>>> On Fri, Jun 27, 2014 at 07:57:38AM -0400, Josh Boyer wrote:
>>>> Hi All,
>>>>
>>>> We've had a report[1] of the virt_blk driver causing a lot of spew
>>>> because it's calling a sleeping function from an invalid context. The
>>>> backtrace is below. This is with kernel v3.16-rc2-69-gd91d66e88ea9.
>>>
>>> Hi Jens, pls see below - it looks like the call to blk_mq_end_io
>>> from IRQ context is causing the issue.
>>> IIUC you switched virtio to this from __blk_end_request_all in
>>>
>>> commit 1cf7e9c68fe84248174e998922b39e508375e7c1
>>> virtio_blk: blk-mq support
>>>
>>> Is this always safe?
>>> I note that at least one other driver is doing this:
>>> drivers/block/mtip32xx/mtip32xx.c
>>
>> Just like __blk_end_request_all blk_mq_end_io is supposed to be called
>> from irq context. The problem is that the MD bio end_io handler is calling
>> a sleeping function. Not sure if that's a bug in MD though given the
>> kernfs symbols in the all trace and the recent churn in that area.
>
> My understanding is this:
>
> bitmap_endwrite -> calls sysfs_notify_dirent_safe under spinlock
> -> calls kernfs_notify which takes a mutex.
>
> So I am guessing it is this commit:
>
> commit d911d98748018f7c8facc035ba39c30f5cce6f9c
> Author: Tejun Heo <[email protected]>
> Date: Wed Apr 9 11:07:31 2014 -0400
>
> kernfs: make kernfs_notify() trigger inotify events too
>
> Tejun, what do you think?
>
> Josh, Brian, could you try reverting that commit to see if it helps?

That definitely be a bug. If you need to block off ->bi_end_io(), just
must punt to a worker thread.

--
Jens Axboe

2014-06-30 20:17:46

by Tejun Heo

[permalink] [raw]

Subject: Re: virt_blk BUG: sleeping function called from invalid context

On Sun, Jun 29, 2014 at 02:55:36PM -0600, Jens Axboe wrote:
> > commit d911d98748018f7c8facc035ba39c30f5cce6f9c
> > Author: Tejun Heo <[email protected]>
> > Date: Wed Apr 9 11:07:31 2014 -0400
> >
> > kernfs: make kernfs_notify() trigger inotify events too
> >
> > Tejun, what do you think?
> >
> > Josh, Brian, could you try reverting that commit to see if it helps?
>
> That definitely be a bug. If you need to block off ->bi_end_io(), just
> must punt to a worker thread.

Ugh... didn't realize we had users triggering sysfs notifications from
an atomic context. fsnotify support requires sleepable context.
Guess I'll have to punt it to a work item. :(

Thanks.

--
tejun

2014-07-01 20:41:10

by Tejun Heo

[permalink] [raw]

Subject: [PATCH driver-core-linus] kernfs: kernfs_notify() must be useable from non-sleepable contexts

d911d9874801 ("kernfs: make kernfs_notify() trigger inotify events
too") added fsnotify triggering to kernfs_notify() which requires a
sleepable context. There are already existing users of
kernfs_notify() which invoke it from an atomic context and in general
it's silly to require a sleepable context for triggering a
notification.

The following is an invalid context bug triggerd by md invoking
sysfs_notify() from IO completion path.

BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586
in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
2 locks held by swapper/1/0:
#0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>] virtblk_done+0x42/0xe0 [virtio_blk]
#1: (&(&bitmap->counts.lock)->rlock){-.....}, at: [<ffffffff81633718>] bitmap_endwrite+0x68/0x240
irq event stamp: 33518
hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230
hardirqs last disabled at (33516): [<ffffffff818122ed>] common_interrupt+0x6d/0x72
softirqs last enabled at (33518): [<ffffffff810a1272>] _local_bh_enable+0x22/0x50
softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
0000000000000000 f90db13964f4ee05 ffff88007d403b80 ffffffff81807b4c
0000000000000000 ffff88007d403ba8 ffffffff810d4f14 0000000000000000
0000000000441800 ffff880078fa1780 ffff88007d403c38 ffffffff8180caf2
Call Trace:
<IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66
[<ffffffff810d4f14>] __might_sleep+0x184/0x240
[<ffffffff8180caf2>] mutex_lock_nested+0x42/0x440
[<ffffffff812d76a0>] kernfs_notify+0x90/0x150
[<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240
[<ffffffffa00de863>] close_write+0x93/0xb0 [raid1]
[<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1]
[<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1]
[<ffffffff813acb8b>] bio_endio+0x6b/0xa0
[<ffffffff813b46c4>] blk_update_request+0x94/0x420
[<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70
[<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk]
[<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120
[<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30
[<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk]
[<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring]
[<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340
[<ffffffff8111647d>] handle_irq_event+0x3d/0x60
[<ffffffff81119436>] handle_edge_irq+0x66/0x130
[<ffffffff8101c3e4>] handle_irq+0x84/0x150
[<ffffffff818146ad>] do_IRQ+0x4d/0xe0
[<ffffffff818122f2>] common_interrupt+0x72/0x72
<EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10
[<ffffffff81025454>] default_idle+0x24/0x230
[<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20
[<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0
[<ffffffff8104df1b>] start_secondary+0x25b/0x300

This patch fixes it by punting the notification delivery through a
work item. This ends up adding an extra pointer to kernfs_elem_attr
enlarging kernfs_node by a pointer, which is not ideal but not a very
big deal either. If this turns out to be an actual issue, we can move
kernfs_elem_attr->size to kernfs_node->iattr later.

Signed-off-by: Tejun Heo <[email protected]>
Reported-by: Josh Boyer <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Jens Axboe <[email protected]>
---
fs/kernfs/file.c | 69 +++++++++++++++++++++++++++++++++++++++----------
include/linux/kernfs.h | 1
2 files changed, 56 insertions(+), 14 deletions(-)

--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -39,6 +39,19 @@ struct kernfs_open_node {
struct list_head files; /* goes through kernfs_open_file.list */
};

+/*
+ * kernfs_notify() may be called from any context and bounces notifications
+ * through a work item. To minimize space overhead in kernfs_node, the
+ * pending queue is implemented as a singly linked list of kernfs_nodes.
+ * The list is terminated with the self pointer so that whether a
+ * kernfs_node is on the list or not can be determined by testing the next
+ * pointer for NULL.
+ */
+#define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list)
+
+static DEFINE_SPINLOCK(kernfs_notify_lock);
+static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL;
+
static struct kernfs_open_file *kernfs_of(struct file *file)
{
return ((struct seq_file *)file->private_data)->private;
@@ -783,24 +796,25 @@ static unsigned int kernfs_fop_poll(stru
return DEFAULT_POLLMASK|POLLERR|POLLPRI;
}

-/**
- * kernfs_notify - notify a kernfs file
- * @kn: file to notify
- *
- * Notify @kn such that poll(2) on @kn wakes up.
- */
-void kernfs_notify(struct kernfs_node *kn)
+static void kernfs_notify_workfn(struct work_struct *work)
{
- struct kernfs_root *root = kernfs_root(kn);
+ struct kernfs_node *kn;
struct kernfs_open_node *on;
struct kernfs_super_info *info;
- unsigned long flags;
-
- if (WARN_ON(kernfs_type(kn) != KERNFS_FILE))
+repeat:
+ /* pop one off the notify_list */
+ spin_lock_irq(&kernfs_notify_lock);
+ kn = kernfs_notify_list;
+ if (kn == KERNFS_NOTIFY_EOL) {
+ spin_unlock_irq(&kernfs_notify_lock);
return;
+ }
+ kernfs_notify_list = kn->attr.notify_next;
+ kn->attr.notify_next = NULL;
+ spin_unlock_irq(&kernfs_notify_lock);

/* kick poll */
- spin_lock_irqsave(&kernfs_open_node_lock, flags);
+ spin_lock_irq(&kernfs_open_node_lock);

on = kn->attr.open;
if (on) {
@@ -808,12 +822,12 @@ void kernfs_notify(struct kernfs_node *k
wake_up_interruptible(&on->poll);
}

- spin_unlock_irqrestore(&kernfs_open_node_lock, flags);
+ spin_unlock_irq(&kernfs_open_node_lock);

/* kick fsnotify */
mutex_lock(&kernfs_mutex);

- list_for_each_entry(info, &root->supers, node) {
+ list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
struct inode *inode;
struct dentry *dentry;

@@ -833,6 +847,33 @@ void kernfs_notify(struct kernfs_node *k
}

mutex_unlock(&kernfs_mutex);
+ kernfs_put(kn);
+ goto repeat;
+}
+
+/**
+ * kernfs_notify - notify a kernfs file
+ * @kn: file to notify
+ *
+ * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any
+ * context.
+ */
+void kernfs_notify(struct kernfs_node *kn)
+{
+ static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn);
+ unsigned long flags;
+
+ if (WARN_ON(kernfs_type(kn) != KERNFS_FILE))
+ return;
+
+ spin_lock_irqsave(&kernfs_notify_lock, flags);
+ if (!kn->attr.notify_next) {
+ kernfs_get(kn);
+ kn->attr.notify_next = kernfs_notify_list;
+ kernfs_notify_list = kn;
+ schedule_work(&kernfs_notify_work);
+ }
+ spin_unlock_irqrestore(&kernfs_notify_lock, flags);
}
EXPORT_SYMBOL_GPL(kernfs_notify);

--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -91,6 +91,7 @@ struct kernfs_elem_attr {
const struct kernfs_ops *ops;
struct kernfs_open_node *open;
loff_t size;
+ struct kernfs_node *notify_next; /* for kernfs_notify() */
};

/*

2014-07-01 22:43:26

by Greg Kroah-Hartman

[permalink] [raw]

Subject: Re: [PATCH driver-core-linus] kernfs: kernfs_notify() must be useable from non-sleepable contexts

2014-07-02 06:51:57

by Michael S. Tsirkin

[permalink] [raw]

Subject: Re: [PATCH driver-core-linus] kernfs: kernfs_notify() must be useable from non-sleepable contexts

On Tue, Jul 01, 2014 at 04:41:03PM -0400, Tejun Heo wrote:
> d911d9874801 ("kernfs: make kernfs_notify() trigger inotify events
> too") added fsnotify triggering to kernfs_notify() which requires a
> sleepable context. There are already existing users of
> kernfs_notify() which invoke it from an atomic context and in general
> it's silly to require a sleepable context for triggering a
> notification.
>
> The following is an invalid context bug triggerd by md invoking
> sysfs_notify() from IO completion path.
>
> BUG: sleeping function called from invalid context at kernel/locking/mutex.c:586
> in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
> 2 locks held by swapper/1/0:
> #0: (&(&vblk->vq_lock)->rlock){-.-...}, at: [<ffffffffa0039042>] virtblk_done+0x42/0xe0 [virtio_blk]
> #1: (&(&bitmap->counts.lock)->rlock){-.....}, at: [<ffffffff81633718>] bitmap_endwrite+0x68/0x240
> irq event stamp: 33518
> hardirqs last enabled at (33515): [<ffffffff8102544f>] default_idle+0x1f/0x230
> hardirqs last disabled at (33516): [<ffffffff818122ed>] common_interrupt+0x6d/0x72
> softirqs last enabled at (33518): [<ffffffff810a1272>] _local_bh_enable+0x22/0x50
> softirqs last disabled at (33517): [<ffffffff810a29e0>] irq_enter+0x60/0x80
> CPU: 1 PID: 0 Comm: swapper/1 Not tainted 3.16.0-0.rc2.git2.1.fc21.x86_64 #1
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> 0000000000000000 f90db13964f4ee05 ffff88007d403b80 ffffffff81807b4c
> 0000000000000000 ffff88007d403ba8 ffffffff810d4f14 0000000000000000
> 0000000000441800 ffff880078fa1780 ffff88007d403c38 ffffffff8180caf2
> Call Trace:
> <IRQ> [<ffffffff81807b4c>] dump_stack+0x4d/0x66
> [<ffffffff810d4f14>] __might_sleep+0x184/0x240
> [<ffffffff8180caf2>] mutex_lock_nested+0x42/0x440
> [<ffffffff812d76a0>] kernfs_notify+0x90/0x150
> [<ffffffff8163377c>] bitmap_endwrite+0xcc/0x240
> [<ffffffffa00de863>] close_write+0x93/0xb0 [raid1]
> [<ffffffffa00df029>] r1_bio_write_done+0x29/0x50 [raid1]
> [<ffffffffa00e0474>] raid1_end_write_request+0xe4/0x260 [raid1]
> [<ffffffff813acb8b>] bio_endio+0x6b/0xa0
> [<ffffffff813b46c4>] blk_update_request+0x94/0x420
> [<ffffffff813bf0ea>] blk_mq_end_io+0x1a/0x70
> [<ffffffffa00392c2>] virtblk_request_done+0x32/0x80 [virtio_blk]
> [<ffffffff813c0648>] __blk_mq_complete_request+0x88/0x120
> [<ffffffff813c070a>] blk_mq_complete_request+0x2a/0x30
> [<ffffffffa0039066>] virtblk_done+0x66/0xe0 [virtio_blk]
> [<ffffffffa002535a>] vring_interrupt+0x3a/0xa0 [virtio_ring]
> [<ffffffff81116177>] handle_irq_event_percpu+0x77/0x340
> [<ffffffff8111647d>] handle_irq_event+0x3d/0x60
> [<ffffffff81119436>] handle_edge_irq+0x66/0x130
> [<ffffffff8101c3e4>] handle_irq+0x84/0x150
> [<ffffffff818146ad>] do_IRQ+0x4d/0xe0
> [<ffffffff818122f2>] common_interrupt+0x72/0x72
> <EOI> [<ffffffff8105f706>] ? native_safe_halt+0x6/0x10
> [<ffffffff81025454>] default_idle+0x24/0x230
> [<ffffffff81025f9f>] arch_cpu_idle+0xf/0x20
> [<ffffffff810f5adc>] cpu_startup_entry+0x37c/0x7b0
> [<ffffffff8104df1b>] start_secondary+0x25b/0x300
>
> This patch fixes it by punting the notification delivery through a
> work item. This ends up adding an extra pointer to kernfs_elem_attr
> enlarging kernfs_node by a pointer, which is not ideal but not a very
> big deal either. If this turns out to be an actual issue, we can move
> kernfs_elem_attr->size to kernfs_node->iattr later.
>
> Signed-off-by: Tejun Heo <[email protected]>
> Reported-by: Josh Boyer <[email protected]>
> Cc: "Michael S. Tsirkin" <[email protected]>
> Cc: Jens Axboe <[email protected]>

FWIW

Reviewed-by: Michael S. Tsirkin <[email protected]>

> ---
> fs/kernfs/file.c | 69 +++++++++++++++++++++++++++++++++++++++----------
> include/linux/kernfs.h | 1
> 2 files changed, 56 insertions(+), 14 deletions(-)
>
> --- a/fs/kernfs/file.c
> +++ b/fs/kernfs/file.c
> @@ -39,6 +39,19 @@ struct kernfs_open_node {
> struct list_head files; /* goes through kernfs_open_file.list */
> };
>
> +/*
> + * kernfs_notify() may be called from any context and bounces notifications
> + * through a work item. To minimize space overhead in kernfs_node, the
> + * pending queue is implemented as a singly linked list of kernfs_nodes.
> + * The list is terminated with the self pointer so that whether a
> + * kernfs_node is on the list or not can be determined by testing the next
> + * pointer for NULL.
> + */
> +#define KERNFS_NOTIFY_EOL ((void *)&kernfs_notify_list)
> +
> +static DEFINE_SPINLOCK(kernfs_notify_lock);
> +static struct kernfs_node *kernfs_notify_list = KERNFS_NOTIFY_EOL;
> +
> static struct kernfs_open_file *kernfs_of(struct file *file)
> {
> return ((struct seq_file *)file->private_data)->private;
> @@ -783,24 +796,25 @@ static unsigned int kernfs_fop_poll(stru
> return DEFAULT_POLLMASK|POLLERR|POLLPRI;
> }
>
> -/**
> - * kernfs_notify - notify a kernfs file
> - * @kn: file to notify
> - *
> - * Notify @kn such that poll(2) on @kn wakes up.
> - */
> -void kernfs_notify(struct kernfs_node *kn)
> +static void kernfs_notify_workfn(struct work_struct *work)
> {
> - struct kernfs_root *root = kernfs_root(kn);
> + struct kernfs_node *kn;
> struct kernfs_open_node *on;
> struct kernfs_super_info *info;
> - unsigned long flags;
> -
> - if (WARN_ON(kernfs_type(kn) != KERNFS_FILE))
> +repeat:
> + /* pop one off the notify_list */
> + spin_lock_irq(&kernfs_notify_lock);
> + kn = kernfs_notify_list;
> + if (kn == KERNFS_NOTIFY_EOL) {
> + spin_unlock_irq(&kernfs_notify_lock);
> return;
> + }
> + kernfs_notify_list = kn->attr.notify_next;
> + kn->attr.notify_next = NULL;
> + spin_unlock_irq(&kernfs_notify_lock);
>
> /* kick poll */
> - spin_lock_irqsave(&kernfs_open_node_lock, flags);
> + spin_lock_irq(&kernfs_open_node_lock);
>
> on = kn->attr.open;
> if (on) {
> @@ -808,12 +822,12 @@ void kernfs_notify(struct kernfs_node *k
> wake_up_interruptible(&on->poll);
> }
>
> - spin_unlock_irqrestore(&kernfs_open_node_lock, flags);
> + spin_unlock_irq(&kernfs_open_node_lock);
>
> /* kick fsnotify */
> mutex_lock(&kernfs_mutex);
>
> - list_for_each_entry(info, &root->supers, node) {
> + list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
> struct inode *inode;
> struct dentry *dentry;
>
> @@ -833,6 +847,33 @@ void kernfs_notify(struct kernfs_node *k
> }
>
> mutex_unlock(&kernfs_mutex);
> + kernfs_put(kn);
> + goto repeat;
> +}
> +
> +/**
> + * kernfs_notify - notify a kernfs file
> + * @kn: file to notify
> + *
> + * Notify @kn such that poll(2) on @kn wakes up. Maybe be called from any
> + * context.
> + */
> +void kernfs_notify(struct kernfs_node *kn)
> +{
> + static DECLARE_WORK(kernfs_notify_work, kernfs_notify_workfn);
> + unsigned long flags;
> +
> + if (WARN_ON(kernfs_type(kn) != KERNFS_FILE))
> + return;
> +
> + spin_lock_irqsave(&kernfs_notify_lock, flags);
> + if (!kn->attr.notify_next) {
> + kernfs_get(kn);
> + kn->attr.notify_next = kernfs_notify_list;
> + kernfs_notify_list = kn;
> + schedule_work(&kernfs_notify_work);
> + }
> + spin_unlock_irqrestore(&kernfs_notify_lock, flags);
> }
> EXPORT_SYMBOL_GPL(kernfs_notify);
>
> --- a/include/linux/kernfs.h
> +++ b/include/linux/kernfs.h
> @@ -91,6 +91,7 @@ struct kernfs_elem_attr {
> const struct kernfs_ops *ops;
> struct kernfs_open_node *open;
> loff_t size;
> + struct kernfs_node *notify_next; /* for kernfs_notify() */
> };
>
> /*

2014-07-02 14:14:22

by Tejun Heo

[permalink] [raw]

Subject: Re: [PATCH driver-core-linus] kernfs: kernfs_notify() must be useable from non-sleepable contexts

Hello,

On Tue, Jul 01, 2014 at 01:51:48PM -0700, Greg Kroah-Hartman wrote:
> Looks good to me, do you want to take this with your other kernfs
> patches for 3.16-final? Or if you don't have that, I can take it
> through my tree, it's your choice, either is fine for me.
>
> If you want it in your tree, feel free to add:
> Acked-by: Greg Kroah-Hartman <[email protected]>

The other kernfs changes are cgroup specific and in
cgroup/for-3.16-fixes. I think this one fits better in the driver
core tree. Can you please route it?

Thanks!

--
tejun

2014-07-02 16:32:16

by Greg Kroah-Hartman

[permalink] [raw]

Subject: Re: [PATCH driver-core-linus] kernfs: kernfs_notify() must be useable from non-sleepable contexts

On Wed, Jul 02, 2014 at 10:14:16AM -0400, Tejun Heo wrote:
> Hello,
>
> On Tue, Jul 01, 2014 at 01:51:48PM -0700, Greg Kroah-Hartman wrote:
> > Looks good to me, do you want to take this with your other kernfs
> > patches for 3.16-final? Or if you don't have that, I can take it
> > through my tree, it's your choice, either is fine for me.
> >
> > If you want it in your tree, feel free to add:
> > Acked-by: Greg Kroah-Hartman <[email protected]>
>
> The other kernfs changes are cgroup specific and in
> cgroup/for-3.16-fixes. I think this one fits better in the driver
> core tree. Can you please route it?

Sure, will queue it up now.

greg k-h