On Mon, 2013-03-25 at 20:47 +0700, Emmanuel Benisty wrote: > On Mon, Mar 25, 2013 at 12:10 AM, Linus Torvalds > <torva...@linux-foundation.org> wrote: > > And you never see this problem without Rik's patches? > > No, never. > > > Could you bisect > > *which* patch it starts with? Are the first four ones ok (the moving > > of the locking around, but without the fine-grained ones), for > > example? > > With the first four patches only, I got some X server freeze (just tried > once).
Going over the code again, I found a potential recursive spinlock scenario. Andrew, if you have no objections, please queue this up. Thanks. ---8<--- From: Davidlohr Bueso <davidlohr.bu...@hp.com> Subject: [PATCH] ipc, sem: prevent possible deadlock In semctl_main(), when cmd == GETALL, we're locking sma->sem_perm.lock (through sem_lock_and_putref), yet after the conditional, we lock it again. Unlock sma right after exiting the conditional. Signed-off-by: Davidlohr Bueso <davidlohr.bu...@hp.com> --- ipc/sem.c | 1 + 1 file changed, 1 insertion(+) diff --git a/ipc/sem.c b/ipc/sem.c index 1a2913d..f257afe 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -1243,6 +1243,7 @@ static int semctl_main(struct ipc_namespace *ns, int semid, int semnum, err = -EIDRM; goto out_free; } + sem_unlock(sma, -1); } sem_lock(sma, NULL, -1); -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/