Messages in this thread Patch in this message | | | Date | Wed, 22 Dec 2021 12:45:33 +0100 | Subject | Re: [PATCH] ipc/sem: do not sleep with a spin lock held | From | Manfred Spraul <> |
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Hi Minghao,
On 12/22/21 09:10, 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. > > Reported-by: Zeal Robot <zealci@zte.com.cn> > Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Could you add
Fixes: fc37a3b8b438 ("[PATCH] ipc sem: use kvmalloc for sem_undo allocation")
Cc: stable@vger.kernel.org
I will review/test the change in the next few days.
Especially, I would like to check if there are further instances where the same mistake was made.
> /** > * kvfree() - Free memory. > * @addr: Pointer to allocated memory. > * > * kvfree frees memory allocated by any of vmalloc(), kmalloc() or > kvmalloc(). > * It is slightly more efficient to use kfree() or vfree() if you are > certain > * that you know which one to use. > * > * Context: Either preemptible task context or not-NMI interrupt. > */ > As an independent change: Should we add a
might_sleep_if(!in_interrupt());
into kvfree(), to trigger bugs more easily?
> --- > 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;
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