* [PATCH] drm/amdgpu: Fix blocking in RCU critical section(v2)
@ 2017-07-20 2:46 Alex Xie
[not found] ` <1500518816-12399-1-git-send-email-AlexBin.Xie-5C7GfCeVMHo@public.gmane.org>
0 siblings, 1 reply; 5+ messages in thread
From: Alex Xie @ 2017-07-20 2:46 UTC (permalink / raw)
To: amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW; +Cc: Alex Xie
In RCU read-side critical sections, blocking or sleeping is prohibited.
v2: Unlock RCU for the code path where result==NULL. (David Zhou)
Update subject
Tested-by and reported by: Dave Airlie <airlied@redhat.com>
[ 141.965723] =============================
[ 141.965724] WARNING: suspicious RCU usage
[ 141.965726] 4.12.0-rc7 #221 Not tainted
[ 141.965727] -----------------------------
[ 141.965728] /home/airlied/devel/kernel/linux-2.6/include/linux/rcupdate.h:531
Illegal context switch in RCU read-side critical section!
[ 141.965730]
other info that might help us debug this:
[ 141.965731]
rcu_scheduler_active = 2, debug_locks = 0
[ 141.965732] 1 lock held by amdgpu_cs:0/1332:
[ 141.965733] #0: (rcu_read_lock){......}, at: [<ffffffffa01a0d07>]
amdgpu_bo_list_get+0x0/0x109 [amdgpu]
[ 141.965774]
stack backtrace:
[ 141.965776] CPU: 6 PID: 1332 Comm: amdgpu_cs:0 Not tainted 4.12.0-rc7 #221
[ 141.965777] Hardware name: To be filled by O.E.M. To be filled by
O.E.M./M5A97 R2.0, BIOS 2603 06/26/2015
[ 141.965778] Call Trace:
[ 141.965782] dump_stack+0x68/0x92
[ 141.965785] lockdep_rcu_suspicious+0xf7/0x100
[ 141.965788] ___might_sleep+0x56/0x1fc
[ 141.965790] __might_sleep+0x68/0x6f
[ 141.965793] __mutex_lock+0x4e/0x7b5
[ 141.965817] ? amdgpu_bo_list_get+0xa4/0x109 [amdgpu]
[ 141.965820] ? lock_acquire+0x125/0x1b9
[ 141.965844] ? amdgpu_bo_list_set+0x464/0x464 [amdgpu]
[ 141.965846] mutex_lock_nested+0x16/0x18
[ 141.965848] ? mutex_lock_nested+0x16/0x18
[ 141.965872] amdgpu_bo_list_get+0xa4/0x109 [amdgpu]
[ 141.965895] amdgpu_cs_ioctl+0x4a0/0x17dd [amdgpu]
[ 141.965898] ? radix_tree_node_alloc.constprop.11+0x77/0xab
[ 141.965916] drm_ioctl+0x264/0x393 [drm]
[ 141.965939] ? amdgpu_cs_find_mapping+0x83/0x83 [amdgpu]
[ 141.965942] ? trace_hardirqs_on_caller+0x16a/0x186
Signed-off-by: Alex Xie <AlexBin.Xie@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
index dc87962..e5d61fe 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c
@@ -198,12 +198,18 @@ amdgpu_bo_list_get(struct amdgpu_fpriv *fpriv, int id)
result = idr_find(&fpriv->bo_list_handles, id);
if (result) {
- if (kref_get_unless_zero(&result->refcount))
+ if (kref_get_unless_zero(&result->refcount)) {
+ rcu_read_unlock();
mutex_lock(&result->lock);
- else
+ }
+ else {
+ rcu_read_unlock();
result = NULL;
+ }
+ }
+ else {
+ rcu_read_unlock();
}
- rcu_read_unlock();
return result;
}
--
2.7.4
_______________________________________________
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx
^ permalink raw reply related [flat|nested] 5+ messages in thread[parent not found: <1500518816-12399-1-git-send-email-AlexBin.Xie-5C7GfCeVMHo@public.gmane.org>]
* Re: [PATCH] drm/amdgpu: Fix blocking in RCU critical section(v2) [not found] ` <1500518816-12399-1-git-send-email-AlexBin.Xie-5C7GfCeVMHo@public.gmane.org> @ 2017-07-20 3:01 ` zhoucm1 [not found] ` <59701D10.3020405-5C7GfCeVMHo@public.gmane.org> 2017-07-20 18:29 ` Emil Velikov 1 sibling, 1 reply; 5+ messages in thread From: zhoucm1 @ 2017-07-20 3:01 UTC (permalink / raw) To: Alex Xie, amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW one small nit pick, with that fix, Reviewed-by: Chunming Zhou <david1.zhou@amd.com> On 2017年07月20日 10:46, Alex Xie wrote: > In RCU read-side critical sections, blocking or sleeping is prohibited. > > v2: Unlock RCU for the code path where result==NULL. (David Zhou) > Update subject > > Tested-by and reported by: Dave Airlie <airlied@redhat.com> > > [ 141.965723] ============================= > [ 141.965724] WARNING: suspicious RCU usage > [ 141.965726] 4.12.0-rc7 #221 Not tainted > [ 141.965727] ----------------------------- > [ 141.965728] /home/airlied/devel/kernel/linux-2.6/include/linux/rcupdate.h:531 > Illegal context switch in RCU read-side critical section! > [ 141.965730] > other info that might help us debug this: > > [ 141.965731] > rcu_scheduler_active = 2, debug_locks = 0 > [ 141.965732] 1 lock held by amdgpu_cs:0/1332: > [ 141.965733] #0: (rcu_read_lock){......}, at: [<ffffffffa01a0d07>] > amdgpu_bo_list_get+0x0/0x109 [amdgpu] > [ 141.965774] > stack backtrace: > [ 141.965776] CPU: 6 PID: 1332 Comm: amdgpu_cs:0 Not tainted 4.12.0-rc7 #221 > [ 141.965777] Hardware name: To be filled by O.E.M. To be filled by > O.E.M./M5A97 R2.0, BIOS 2603 06/26/2015 > [ 141.965778] Call Trace: > [ 141.965782] dump_stack+0x68/0x92 > [ 141.965785] lockdep_rcu_suspicious+0xf7/0x100 > [ 141.965788] ___might_sleep+0x56/0x1fc > [ 141.965790] __might_sleep+0x68/0x6f > [ 141.965793] __mutex_lock+0x4e/0x7b5 > [ 141.965817] ? amdgpu_bo_list_get+0xa4/0x109 [amdgpu] > [ 141.965820] ? lock_acquire+0x125/0x1b9 > [ 141.965844] ? amdgpu_bo_list_set+0x464/0x464 [amdgpu] > [ 141.965846] mutex_lock_nested+0x16/0x18 > [ 141.965848] ? mutex_lock_nested+0x16/0x18 > [ 141.965872] amdgpu_bo_list_get+0xa4/0x109 [amdgpu] > [ 141.965895] amdgpu_cs_ioctl+0x4a0/0x17dd [amdgpu] > [ 141.965898] ? radix_tree_node_alloc.constprop.11+0x77/0xab > [ 141.965916] drm_ioctl+0x264/0x393 [drm] > [ 141.965939] ? amdgpu_cs_find_mapping+0x83/0x83 [amdgpu] > [ 141.965942] ? trace_hardirqs_on_caller+0x16a/0x186 > > Signed-off-by: Alex Xie <AlexBin.Xie@amd.com> > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > index dc87962..e5d61fe 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > @@ -198,12 +198,18 @@ amdgpu_bo_list_get(struct amdgpu_fpriv *fpriv, int id) > result = idr_find(&fpriv->bo_list_handles, id); > > if (result) { > - if (kref_get_unless_zero(&result->refcount)) > + if (kref_get_unless_zero(&result->refcount)) { > + rcu_read_unlock(); > mutex_lock(&result->lock); > - else > + } > + else { don't need another line, just like } else { > + rcu_read_unlock(); > result = NULL; > + } > + } > + else { don't need another line, just like } else { > + rcu_read_unlock(); > } > - rcu_read_unlock(); > > return result; > } _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx ^ permalink raw reply [flat|nested] 5+ messages in thread
[parent not found: <59701D10.3020405-5C7GfCeVMHo@public.gmane.org>]
* Re: [PATCH] drm/amdgpu: Fix blocking in RCU critical section(v2) [not found] ` <59701D10.3020405-5C7GfCeVMHo@public.gmane.org> @ 2017-07-20 17:07 ` Christian König 0 siblings, 0 replies; 5+ messages in thread From: Christian König @ 2017-07-20 17:07 UTC (permalink / raw) To: zhoucm1, Alex Xie, amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW Yeah, with the coding style fixed Reviewed-by: Christian König <christian.koenig@amd.com> as well. Christian. Am 20.07.2017 um 05:01 schrieb zhoucm1: > one small nit pick, with that fix, Reviewed-by: Chunming Zhou > <david1.zhou@amd.com> > > On 2017年07月20日 10:46, Alex Xie wrote: >> In RCU read-side critical sections, blocking or sleeping is prohibited. >> >> v2: Unlock RCU for the code path where result==NULL. (David Zhou) >> Update subject >> >> Tested-by and reported by: Dave Airlie <airlied@redhat.com> >> >> [ 141.965723] ============================= >> [ 141.965724] WARNING: suspicious RCU usage >> [ 141.965726] 4.12.0-rc7 #221 Not tainted >> [ 141.965727] ----------------------------- >> [ 141.965728] >> /home/airlied/devel/kernel/linux-2.6/include/linux/rcupdate.h:531 >> Illegal context switch in RCU read-side critical section! >> [ 141.965730] >> other info that might help us debug this: >> >> [ 141.965731] >> rcu_scheduler_active = 2, debug_locks = 0 >> [ 141.965732] 1 lock held by amdgpu_cs:0/1332: >> [ 141.965733] #0: (rcu_read_lock){......}, at: [<ffffffffa01a0d07>] >> amdgpu_bo_list_get+0x0/0x109 [amdgpu] >> [ 141.965774] >> stack backtrace: >> [ 141.965776] CPU: 6 PID: 1332 Comm: amdgpu_cs:0 Not tainted >> 4.12.0-rc7 #221 >> [ 141.965777] Hardware name: To be filled by O.E.M. To be filled by >> O.E.M./M5A97 R2.0, BIOS 2603 06/26/2015 >> [ 141.965778] Call Trace: >> [ 141.965782] dump_stack+0x68/0x92 >> [ 141.965785] lockdep_rcu_suspicious+0xf7/0x100 >> [ 141.965788] ___might_sleep+0x56/0x1fc >> [ 141.965790] __might_sleep+0x68/0x6f >> [ 141.965793] __mutex_lock+0x4e/0x7b5 >> [ 141.965817] ? amdgpu_bo_list_get+0xa4/0x109 [amdgpu] >> [ 141.965820] ? lock_acquire+0x125/0x1b9 >> [ 141.965844] ? amdgpu_bo_list_set+0x464/0x464 [amdgpu] >> [ 141.965846] mutex_lock_nested+0x16/0x18 >> [ 141.965848] ? mutex_lock_nested+0x16/0x18 >> [ 141.965872] amdgpu_bo_list_get+0xa4/0x109 [amdgpu] >> [ 141.965895] amdgpu_cs_ioctl+0x4a0/0x17dd [amdgpu] >> [ 141.965898] ? radix_tree_node_alloc.constprop.11+0x77/0xab >> [ 141.965916] drm_ioctl+0x264/0x393 [drm] >> [ 141.965939] ? amdgpu_cs_find_mapping+0x83/0x83 [amdgpu] >> [ 141.965942] ? trace_hardirqs_on_caller+0x16a/0x186 >> >> Signed-off-by: Alex Xie <AlexBin.Xie@amd.com> >> --- >> drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c | 12 +++++++++--- >> 1 file changed, 9 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c >> b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c >> index dc87962..e5d61fe 100644 >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c >> @@ -198,12 +198,18 @@ amdgpu_bo_list_get(struct amdgpu_fpriv *fpriv, >> int id) >> result = idr_find(&fpriv->bo_list_handles, id); >> if (result) { >> - if (kref_get_unless_zero(&result->refcount)) >> + if (kref_get_unless_zero(&result->refcount)) { >> + rcu_read_unlock(); >> mutex_lock(&result->lock); >> - else >> + } >> + else { > don't need another line, just like } else { >> + rcu_read_unlock(); >> result = NULL; >> + } >> + } >> + else { > don't need another line, just like } else { >> + rcu_read_unlock(); >> } >> - rcu_read_unlock(); >> return result; >> } > > _______________________________________________ > amd-gfx mailing list > amd-gfx@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] drm/amdgpu: Fix blocking in RCU critical section(v2) [not found] ` <1500518816-12399-1-git-send-email-AlexBin.Xie-5C7GfCeVMHo@public.gmane.org> 2017-07-20 3:01 ` zhoucm1 @ 2017-07-20 18:29 ` Emil Velikov [not found] ` <CACvgo53BAk8t-VxxgftA1Un2MUxSW=61=SgNfQEPBm+c9wejtQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 1 sibling, 1 reply; 5+ messages in thread From: Emil Velikov @ 2017-07-20 18:29 UTC (permalink / raw) To: Alex Xie; +Cc: amd-gfx mailing list Hi Alex, On 20 July 2017 at 03:46, Alex Xie <AlexBin.Xie@amd.com> wrote: > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c > @@ -198,12 +198,18 @@ amdgpu_bo_list_get(struct amdgpu_fpriv *fpriv, int id) > result = idr_find(&fpriv->bo_list_handles, id); > > if (result) { > - if (kref_get_unless_zero(&result->refcount)) > + if (kref_get_unless_zero(&result->refcount)) { > + rcu_read_unlock(); > mutex_lock(&result->lock); > - else > + } > + else { > + rcu_read_unlock(); > result = NULL; > + } > + } > + else { > + rcu_read_unlock(); > } > - rcu_read_unlock(); > > return result; A drive-by suggestion - feel free to ignore. The "return early" approach seems great IMHO. The code will be shorter, indentation - less, no {}/else to track plus overall it seems clearer. Namely: result = idr_find(&fpriv->bo_list_handles, id); if (!result || !kref_get_unless_zero(&result->refcount)) { rcu_read_unlock(); return NULL; } rcu_read_unlock(); mutex_lock(&result->lock); return result; } HTH Emil _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx ^ permalink raw reply [flat|nested] 5+ messages in thread
[parent not found: <CACvgo53BAk8t-VxxgftA1Un2MUxSW=61=SgNfQEPBm+c9wejtQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>]
* Re: [PATCH] drm/amdgpu: Fix blocking in RCU critical section(v2) [not found] ` <CACvgo53BAk8t-VxxgftA1Un2MUxSW=61=SgNfQEPBm+c9wejtQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> @ 2017-07-26 14:37 ` axie 0 siblings, 0 replies; 5+ messages in thread From: axie @ 2017-07-26 14:37 UTC (permalink / raw) To: Emil Velikov, Alex Xie; +Cc: amd-gfx mailing list Hi Emil, Sorry for late reply. I was so busy last week and this week. Your logic looks correct, smarter and shorter. I feel relatively more difficult to understand the logic, with two "!" and one "||" in the same if statement. Thanks for the advice always. On 2017-07-20 02:29 PM, Emil Velikov wrote: > Hi Alex, > > On 20 July 2017 at 03:46, Alex Xie <AlexBin.Xie@amd.com> wrote: >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bo_list.c >> @@ -198,12 +198,18 @@ amdgpu_bo_list_get(struct amdgpu_fpriv *fpriv, int id) >> result = idr_find(&fpriv->bo_list_handles, id); >> >> if (result) { >> - if (kref_get_unless_zero(&result->refcount)) >> + if (kref_get_unless_zero(&result->refcount)) { >> + rcu_read_unlock(); >> mutex_lock(&result->lock); >> - else >> + } >> + else { >> + rcu_read_unlock(); >> result = NULL; >> + } >> + } >> + else { >> + rcu_read_unlock(); >> } >> - rcu_read_unlock(); >> >> return result; > A drive-by suggestion - feel free to ignore. > > The "return early" approach seems great IMHO. The code will be > shorter, indentation - less, no {}/else to track plus overall it seems > clearer. > Namely: > > result = idr_find(&fpriv->bo_list_handles, id); > > if (!result || !kref_get_unless_zero(&result->refcount)) { > rcu_read_unlock(); > return NULL; > } > > rcu_read_unlock(); > mutex_lock(&result->lock); > return result; > } > > HTH > Emil _______________________________________________ amd-gfx mailing list amd-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/amd-gfx ^ permalink raw reply [flat|nested] 5+ messages in thread
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Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2017-07-20 2:46 [PATCH] drm/amdgpu: Fix blocking in RCU critical section(v2) Alex Xie
[not found] ` <1500518816-12399-1-git-send-email-AlexBin.Xie-5C7GfCeVMHo@public.gmane.org>
2017-07-20 3:01 ` zhoucm1
[not found] ` <59701D10.3020405-5C7GfCeVMHo@public.gmane.org>
2017-07-20 17:07 ` Christian König
2017-07-20 18:29 ` Emil Velikov
[not found] ` <CACvgo53BAk8t-VxxgftA1Un2MUxSW=61=SgNfQEPBm+c9wejtQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-07-26 14:37 ` axie
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