From: Minghao Chi chi.minghao@zte.com.cn
We can't call kvfree() with a spin lock held, so defer it. Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Reported-by: Zeal Robot zealci@zte.com.cn Signed-off-by: Minghao Chi chi.minghao@zte.com.cn --- changelog since v2: + Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo + allocation") ipc/sem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c index 6693daf4fe11..0dbdb98fdf2d 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -1964,6 +1964,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) */ un = lookup_undo(ulp, semid); if (un) { + spin_unlock(&ulp->lock); kvfree(new); goto success; } @@ -1976,9 +1977,8 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) ipc_assert_locked_object(&sma->sem_perm); list_add(&new->list_id, &sma->list_id); un = new; - -success: spin_unlock(&ulp->lock); +success: sem_unlock(sma, -1); out: return un; -- 2.25.1
On 23. 12. 21, 4:12, cgel.zte@gmail.com wrote:
From: Minghao Chi chi.minghao@zte.com.cn
We can't call kvfree() with a spin lock held, so defer it.
Sorry, defer what?
There are attempts to fix kvfree instead, not sure which of these approaches (fix kvfree or its callers) won in the end?
Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Reported-by: Zeal Robot zealci@zte.com.cn Signed-off-by: Minghao Chi chi.minghao@zte.com.cn
changelog since v2:
- Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo
- allocation") ipc/sem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/ipc/sem.c b/ipc/sem.c index 6693daf4fe11..0dbdb98fdf2d 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -1964,6 +1964,7 @@ static struct sem_undo *find_alloc_undo(struct ipc_namespace *ns, int semid) */ un = lookup_undo(ulp, semid); if (un) {
spin_unlock(&ulp->lock);
Hi Jiri,
On 1/3/22 10:27, Jiri Slaby wrote:
On 23. 12. 21, 4:12, cgel.zte@gmail.com wrote:
From: Minghao Chi chi.minghao@zte.com.cn
We can't call kvfree() with a spin lock held, so defer it.
Sorry, defer what?
First drop the spinlock, then call kvfree().
There are attempts to fix kvfree instead, not sure which of these approaches (fix kvfree or its callers) won in the end?
Exactly. We have three options - but noone volunteered yet to decide:
- change ipc/sem.c [minimal change]
- change kvfree() to use vfree_atomic() [would also fix other changes that did s/kfree/kvfree/]
- Modify the vma handling so that it becomes safe to call vfree() while holding a spinlock. [perfect approach, but I'm concerned about side effects]
--
Manfred
On Mon, Jan 3, 2022 at 9:18 AM Manfred Spraul manfred@colorfullife.com wrote:
Hi Jiri,
On 1/3/22 10:27, Jiri Slaby wrote:
On 23. 12. 21, 4:12, cgel.zte@gmail.com wrote:
From: Minghao Chi chi.minghao@zte.com.cn
We can't call kvfree() with a spin lock held, so defer it.
Sorry, defer what?
First drop the spinlock, then call kvfree().
There are attempts to fix kvfree instead, not sure which of these approaches (fix kvfree or its callers) won in the end?
Exactly. We have three options - but noone volunteered yet to decide:
- change ipc/sem.c [minimal change]
Let's go with the minimal change for now which can easily be cherry-picked for the stable tree. It seems other approaches need more work/discussion.
- change kvfree() to use vfree_atomic() [would also fix other changes
that did s/kfree/kvfree/]
- Modify the vma handling so that it becomes safe to call vfree() while
holding a spinlock. [perfect approach, but I'm concerned about side effects]
--
Manfred
On Wed, Dec 22, 2021 at 7:12 PM cgel.zte@gmail.com wrote:
From: Minghao Chi chi.minghao@zte.com.cn
We can't call kvfree() with a spin lock held, so defer it. Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Reported-by: Zeal Robot zealci@zte.com.cn Signed-off-by: Minghao Chi chi.minghao@zte.com.cn
Reviewed-by: Shakeel Butt shakeelb@google.com
On 1/4/22 19:20, Shakeel Butt wrote:
On Wed, Dec 22, 2021 at 7:12 PM cgel.zte@gmail.com wrote:
From: Minghao Chi chi.minghao@zte.com.cn
We can't call kvfree() with a spin lock held, so defer it. Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Reported-by: Zeal Robot zealci@zte.com.cn Signed-off-by: Minghao Chi chi.minghao@zte.com.cn
Reviewed-by: Shakeel Butt shakeelb@google.com
Reviewed-by: Manfred Spraul manfred@colorfullife.com
--
Manfred
linux-stable-mirror@lists.linaro.org
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cgel.zte＠gmail.com -
Jiri Slaby -
Manfred Spraul -
Shakeel Butt