| Message ID | 20220602192020.166940-2-longman@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blk-cgroup: Optimize blkcg_rstat_flush() | expand |
On Thu, Jun 02, 2022 at 03:20:18PM -0400, Waiman Long wrote: > Commit f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup > rstat") changes block cgroup IO stats to use the rstat APIs. It added > a new percpu iostat_cpu field into blkg. The blkg_alloc() was modified > to allocate the new percpu iostat_cpu but didn't free it when an error > happened. Fix this by freeing the percpu iostat_cpu on error exit. > > Fixes: f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") > Signed-off-by: Waiman Long <longman@redhat.com> > Acked-by: Tejun Heo <tj@kernel.org> > --- > block/blk-cgroup.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c > index 40161a3f68d0..acd9b0aa8dc8 100644 > --- a/block/blk-cgroup.c > +++ b/block/blk-cgroup.c > @@ -219,11 +219,11 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, > return NULL; > > if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) > - goto err_free; > + goto err_free_blkg; > > blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); > if (!blkg->iostat_cpu) > - goto err_free; > + goto err_free_blkg; > > if (!blk_get_queue(q)) > goto err_free; > @@ -259,6 +259,9 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, > return blkg; > > err_free: > + free_percpu(blkg->iostat_cpu); > + > +err_free_blkg: > blkg_free(blkg); Hi Waiman, But blkg_free() frees blkg->iostat_cpu via blkg_free_workfn(), so I am confused where the leak is in failure path? Thanks Ming
On 6/3/22 22:08, Ming Lei wrote: > On Thu, Jun 02, 2022 at 03:20:18PM -0400, Waiman Long wrote: >> Commit f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup >> rstat") changes block cgroup IO stats to use the rstat APIs. It added >> a new percpu iostat_cpu field into blkg. The blkg_alloc() was modified >> to allocate the new percpu iostat_cpu but didn't free it when an error >> happened. Fix this by freeing the percpu iostat_cpu on error exit. >> >> Fixes: f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") >> Signed-off-by: Waiman Long <longman@redhat.com> >> Acked-by: Tejun Heo <tj@kernel.org> >> --- >> block/blk-cgroup.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c >> index 40161a3f68d0..acd9b0aa8dc8 100644 >> --- a/block/blk-cgroup.c >> +++ b/block/blk-cgroup.c >> @@ -219,11 +219,11 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, >> return NULL; >> >> if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) >> - goto err_free; >> + goto err_free_blkg; >> >> blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); >> if (!blkg->iostat_cpu) >> - goto err_free; >> + goto err_free_blkg; >> >> if (!blk_get_queue(q)) >> goto err_free; >> @@ -259,6 +259,9 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, >> return blkg; >> >> err_free: >> + free_percpu(blkg->iostat_cpu); >> + >> +err_free_blkg: >> blkg_free(blkg); > Hi Waiman, > > But blkg_free() frees blkg->iostat_cpu via blkg_free_workfn(), so I am > confused where the leak is in failure path? Yes, you are right. I have overlooked that. So this patch isn't really necessary. Thanks for correcting me. Cheers, Longman
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 40161a3f68d0..acd9b0aa8dc8 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -219,11 +219,11 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, return NULL; if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) - goto err_free; + goto err_free_blkg; blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); if (!blkg->iostat_cpu) - goto err_free; + goto err_free_blkg; if (!blk_get_queue(q)) goto err_free; @@ -259,6 +259,9 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, return blkg; err_free: + free_percpu(blkg->iostat_cpu); + +err_free_blkg: blkg_free(blkg); return NULL; }
Commit f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") changes block cgroup IO stats to use the rstat APIs. It added a new percpu iostat_cpu field into blkg. The blkg_alloc() was modified to allocate the new percpu iostat_cpu but didn't free it when an error happened. Fix this by freeing the percpu iostat_cpu on error exit. Fixes: f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") Signed-off-by: Waiman Long <longman@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> --- block/blk-cgroup.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)