This is a note to let you know that I've just added the patch titled
bcache: recover data from backing when data is clean
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
bcache-recover-data-from-backing-when-data-is-clean.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From e393aa2446150536929140739f09c6ecbcbea7f0 Mon Sep 17 00:00:00 2001
From: Rui Hua <huarui.dev(a)gmail.com>
Date: Fri, 24 Nov 2017 15:14:26 -0800
Subject: bcache: recover data from backing when data is clean
From: Rui Hua <huarui.dev(a)gmail.com>
commit e393aa2446150536929140739f09c6ecbcbea7f0 upstream.
When we send a read request and hit the clean data in cache device, there
is a situation called cache read race in bcache(see the commit in the tail
of cache_look_up(), the following explaination just copy from there):
The bucket we're reading from might be reused while our bio is in flight,
and we could then end up reading the wrong data. We guard against this
by checking (in bch_cache_read_endio()) if the pointer is stale again;
if so, we treat it as an error (s->iop.error = -EINTR) and reread from
the backing device (but we don't pass that error up anywhere)
It should be noted that cache read race happened under normal
circumstances, not the circumstance when SSD failed, it was counted
and shown in /sys/fs/bcache/XXX/internal/cache_read_races.
Without this patch, when we use writeback mode, we will never reread from
the backing device when cache read race happened, until the whole cache
device is clean, because the condition
(s->recoverable && (dc && !atomic_read(&dc->has_dirty))) is false in
cached_dev_read_error(). In this situation, the s->iop.error(= -EINTR)
will be passed up, at last, user will receive -EINTR when it's bio end,
this is not suitable, and wield to up-application.
In this patch, we use s->read_dirty_data to judge whether the read
request hit dirty data in cache device, it is safe to reread data from
the backing device when the read request hit clean data. This can not
only handle cache read race, but also recover data when failed read
request from cache device.
[edited by mlyle to fix up whitespace, commit log title, comment
spelling]
Fixes: d59b23795933 ("bcache: only permit to recovery read error when cache device is clean")
Signed-off-by: Hua Rui <huarui.dev(a)gmail.com>
Reviewed-by: Michael Lyle <mlyle(a)lyle.org>
Reviewed-by: Coly Li <colyli(a)suse.de>
Signed-off-by: Michael Lyle <mlyle(a)lyle.org>
Signed-off-by: Jens Axboe <axboe(a)kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/md/bcache/request.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -705,16 +705,15 @@ static void cached_dev_read_error(struct
{
struct search *s = container_of(cl, struct search, cl);
struct bio *bio = &s->bio.bio;
- struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
/*
- * If cache device is dirty (dc->has_dirty is non-zero), then
- * recovery a failed read request from cached device may get a
- * stale data back. So read failure recovery is only permitted
- * when cache device is clean.
+ * If read request hit dirty data (s->read_dirty_data is true),
+ * then recovery a failed read request from cached device may
+ * get a stale data back. So read failure recovery is only
+ * permitted when read request hit clean data in cache device,
+ * or when cache read race happened.
*/
- if (s->recoverable &&
- (dc && !atomic_read(&dc->has_dirty))) {
+ if (s->recoverable && !s->read_dirty_data) {
/* Retry from the backing device: */
trace_bcache_read_retry(s->orig_bio);
Patches currently in stable-queue which might be from huarui.dev(a)gmail.com are
queue-3.18/bcache-recover-data-from-backing-when-data-is-clean.patch
This is a note to let you know that I've just added the patch titled
bcache: only permit to recovery read error when cache device is clean
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=sum…
The filename of the patch is:
bcache-only-permit-to-recovery-read-error-when-cache-device-is-clean.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable(a)vger.kernel.org> know about it.
>From d59b23795933678c9638fd20c942d2b4f3cd6185 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli(a)suse.de>
Date: Mon, 30 Oct 2017 14:46:31 -0700
Subject: bcache: only permit to recovery read error when cache device is clean
From: Coly Li <colyli(a)suse.de>
commit d59b23795933678c9638fd20c942d2b4f3cd6185 upstream.
When bcache does read I/Os, for example in writeback or writethrough mode,
if a read request on cache device is failed, bcache will try to recovery
the request by reading from cached device. If the data on cached device is
not synced with cache device, then requester will get a stale data.
For critical storage system like database, providing stale data from
recovery may result an application level data corruption, which is
unacceptible.
With this patch, for a failed read request in writeback or writethrough
mode, recovery a recoverable read request only happens when cache device
is clean. That is to say, all data on cached device is up to update.
For other cache modes in bcache, read request will never hit
cached_dev_read_error(), they don't need this patch.
Please note, because cache mode can be switched arbitrarily in run time, a
writethrough mode might be switched from a writeback mode. Therefore
checking dc->has_data in writethrough mode still makes sense.
Changelog:
V4: Fix parens error pointed by Michael Lyle.
v3: By response from Kent Oversteet, he thinks recovering stale data is a
bug to fix, and option to permit it is unnecessary. So this version
the sysfs file is removed.
v2: rename sysfs entry from allow_stale_data_on_failure to
allow_stale_data_on_failure, and fix the confusing commit log.
v1: initial patch posted.
[small change to patch comment spelling by mlyle]
Signed-off-by: Coly Li <colyli(a)suse.de>
Signed-off-by: Michael Lyle <mlyle(a)lyle.org>
Reported-by: Arne Wolf <awolf(a)lenovo.com>
Reviewed-by: Michael Lyle <mlyle(a)lyle.org>
Cc: Kent Overstreet <kent.overstreet(a)gmail.com>
Cc: Nix <nix(a)esperi.org.uk>
Cc: Kai Krakow <hurikhan77(a)gmail.com>
Cc: Eric Wheeler <bcache(a)lists.ewheeler.net>
Cc: Junhui Tang <tang.junhui(a)zte.com.cn>
Signed-off-by: Jens Axboe <axboe(a)kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
---
drivers/md/bcache/request.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -705,8 +705,16 @@ static void cached_dev_read_error(struct
{
struct search *s = container_of(cl, struct search, cl);
struct bio *bio = &s->bio.bio;
+ struct cached_dev *dc = container_of(s->d, struct cached_dev, disk);
- if (s->recoverable) {
+ /*
+ * If cache device is dirty (dc->has_dirty is non-zero), then
+ * recovery a failed read request from cached device may get a
+ * stale data back. So read failure recovery is only permitted
+ * when cache device is clean.
+ */
+ if (s->recoverable &&
+ (dc && !atomic_read(&dc->has_dirty))) {
/* Retry from the backing device: */
trace_bcache_read_retry(s->orig_bio);
Patches currently in stable-queue which might be from colyli(a)suse.de are
queue-3.18/bcache-only-permit-to-recovery-read-error-when-cache-device-is-clean.patch
queue-3.18/bcache-recover-data-from-backing-when-data-is-clean.patch
get_modes() callback might be called asynchronously from the DRM core and
it is not synchronized with bridge_enable(), which sets proper runtime PM
state of the main DP device. Fix this by calling pm_runtime_get_sync()
before calling drm_get_edid(), which in turn calls drm_dp_i2c_xfer() and
analogix_dp_transfer() to ensure that main DP device is runtime active
when doing any access to its registers.
This fixes the following kernel issue on Samsung Exynos5250 Snow board:
Unhandled fault: imprecise external abort (0x406) at 0x00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: : 406 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 0 PID: 62 Comm: kworker/0:2 Not tainted 4.13.0-rc2-00364-g4a97a3da420b #3357
Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
Workqueue: events output_poll_execute
task: edc14800 task.stack: edcb2000
PC is at analogix_dp_transfer+0x15c/0x2fc
LR is at analogix_dp_transfer+0x134/0x2fc
pc : [<c0468538>] lr : [<c0468510>] psr: 60000013
sp : edcb3be8 ip : 0000002a fp : 00000001
r10: 00000000 r9 : edcb3cd8 r8 : edcb3c40
r7 : 00000000 r6 : edd3b380 r5 : edd3b010 r4 : 00000064
r3 : 00000000 r2 : f0ad3000 r1 : edcb3c40 r0 : edd3b010
Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: 4000406a DAC: 00000051
Process kworker/0:2 (pid: 62, stack limit = 0xedcb2210)
Stack: (0xedcb3be8 to 0xedcb4000)
[<c0468538>] (analogix_dp_transfer) from [<c0424ba4>] (drm_dp_i2c_do_msg+0x8c/0x2b4)
[<c0424ba4>] (drm_dp_i2c_do_msg) from [<c0424e64>] (drm_dp_i2c_xfer+0x98/0x214)
[<c0424e64>] (drm_dp_i2c_xfer) from [<c057b2d8>] (__i2c_transfer+0x140/0x29c)
[<c057b2d8>] (__i2c_transfer) from [<c057b4a4>] (i2c_transfer+0x70/0xe4)
[<c057b4a4>] (i2c_transfer) from [<c0441de4>] (drm_do_probe_ddc_edid+0xb4/0x114)
[<c0441de4>] (drm_do_probe_ddc_edid) from [<c0441e5c>] (drm_probe_ddc+0x18/0x28)
[<c0441e5c>] (drm_probe_ddc) from [<c0445728>] (drm_get_edid+0x124/0x2d4)
[<c0445728>] (drm_get_edid) from [<c0465ea0>] (analogix_dp_get_modes+0x90/0x114)
[<c0465ea0>] (analogix_dp_get_modes) from [<c0425e8c>] (drm_helper_probe_single_connector_modes+0x198/0x68c)
[<c0425e8c>] (drm_helper_probe_single_connector_modes) from [<c04325d4>] (drm_setup_crtcs+0x1b4/0xd18)
[<c04325d4>] (drm_setup_crtcs) from [<c04344a8>] (drm_fb_helper_hotplug_event+0x94/0xd0)
[<c04344a8>] (drm_fb_helper_hotplug_event) from [<c0425a50>] (drm_kms_helper_hotplug_event+0x24/0x28)
[<c0425a50>] (drm_kms_helper_hotplug_event) from [<c04263ec>] (output_poll_execute+0x6c/0x174)
[<c04263ec>] (output_poll_execute) from [<c0136f18>] (process_one_work+0x188/0x3fc)
[<c0136f18>] (process_one_work) from [<c01371f4>] (worker_thread+0x30/0x4b8)
[<c01371f4>] (worker_thread) from [<c013daf8>] (kthread+0x128/0x164)
[<c013daf8>] (kthread) from [<c0108510>] (ret_from_fork+0x14/0x24)
Code: 0a000002 ea000009 e2544001 0a00004a (e59537c8)
---[ end trace cddc7919c79f7878 ]---
Reported-by: Misha Komarovskiy <zombah(a)gmail.com>
CC: stable(a)vger.kernel.org # v4.10+
Signed-off-by: Marek Szyprowski <m.szyprowski(a)samsung.com>
---
This issue was there from the beginning, but recent changes to DRM
core revealed it. It makes sense to backport it to patch f0a8b49c03d2
("drm/bridge: analogix dp: Fix runtime PM state on driver bind"),
which fixed similar issue on driver bind, thus I've marked it for
stable v4.10+.
Best regards
Marek Szyprowski
Samsung R&D Institute Poland
---
drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 5dd3f1cd074a..a8905049b9da 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -946,7 +946,9 @@ static int analogix_dp_get_modes(struct drm_connector *connector)
return 0;
}
+ pm_runtime_get_sync(dp->dev);
edid = drm_get_edid(connector, &dp->aux.ddc);
+ pm_runtime_put(dp->dev);
if (edid) {
drm_mode_connector_update_edid_property(&dp->connector,
edid);
--
2.14.2
>From the shrinker paths, we want to relinquish the GPU and GGTT access to
the object, releasing the backing storage back to the system for
swapout. As a part of that process we would unpin the pages, marking
them for access by the CPU (for the swapout/swapin). However, if that
process was interrupted after unbind the vma, we missed a flush of the
inflight GGTT writes before we made that GTT space available again for
reuse, with the prospect that we would redirect them to another page.
The bug dates back to the introduction of multiple GGTT vma, but the
code itself dates to commit 02bef8f98d26 ("drm/i915: Unbind closed vma
for i915_gem_object_unbind()").
Fixes: 02bef8f98d26 ("drm/i915: Unbind closed vma for i915_gem_object_unbind()")
Fixes: c5ad54cf7dd8 ("drm/i915: Use partial view in mmap fault handler")
Signed-off-by: Chris Wilson <chris(a)chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen(a)linux.intel.com>
Cc: stable(a)vger.kernel.org
Reviewed-by: Joonas Lahtinen <joonas.lahtinen(a)linux.intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e083f242b8dc..80b78fb5daac 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -330,17 +330,10 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj)
* must wait for all rendering to complete to the object (as unbinding
* must anyway), and retire the requests.
*/
- ret = i915_gem_object_wait(obj,
- I915_WAIT_INTERRUPTIBLE |
- I915_WAIT_LOCKED |
- I915_WAIT_ALL,
- MAX_SCHEDULE_TIMEOUT,
- NULL);
+ ret = i915_gem_object_set_to_cpu_domain(obj, false);
if (ret)
return ret;
- i915_gem_retire_requests(to_i915(obj->base.dev));
-
while ((vma = list_first_entry_or_null(&obj->vma_list,
struct i915_vma,
obj_link))) {
--
2.15.1
>From the shrinker paths, we want to relinquish the GPU and GGTT access to
the object, releasing the backing storage back to the system for
swapout. As a part of that process we would unpin the pages, marking
them for access by the CPU (for the swapout/swapin). However, if that
process was interrupted after unbind the vma, we missed a flush of the
inflight GGTT writes before we made that GTT space available again for
reuse, with the prospect that we would redirect them to another page.
The bug dates back to the introduction of multiple GGTT vma, but the
code itself dates to commit 02bef8f98d26 ("drm/i915: Unbind closed vma
for i915_gem_object_unbind()").
Fixes: 02bef8f98d26 ("drm/i915: Unbind closed vma for i915_gem_object_unbind()")
Fixes: c5ad54cf7dd8 ("drm/i915: Use partial view in mmap fault handler")
Signed-off-by: Chris Wilson <chris(a)chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen(a)linux.intel.com>
Cc: stable(a)vger.kernel.org
Reviewed-by: Joonas Lahtinen <joonas.lahtinen(a)linux.intel.com>
---
drivers/gpu/drm/i915/i915_gem.c | 9 +--------
1 file changed, 1 insertion(+), 8 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e083f242b8dc..80b78fb5daac 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -330,17 +330,10 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj)
* must wait for all rendering to complete to the object (as unbinding
* must anyway), and retire the requests.
*/
- ret = i915_gem_object_wait(obj,
- I915_WAIT_INTERRUPTIBLE |
- I915_WAIT_LOCKED |
- I915_WAIT_ALL,
- MAX_SCHEDULE_TIMEOUT,
- NULL);
+ ret = i915_gem_object_set_to_cpu_domain(obj, false);
if (ret)
return ret;
- i915_gem_retire_requests(to_i915(obj->base.dev));
-
while ((vma = list_first_entry_or_null(&obj->vma_list,
struct i915_vma,
obj_link))) {
--
2.15.1