Messages in this thread Patch in this message | | | Date | Mon, 14 Jan 2019 12:25:40 -0500 | From | Steven Rostedt <> | Subject | [PATCH] sbitmap: Protect swap_lock from softirqs |
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From: Steven Rostedt (VMware) <rostedt@goodmis.org>
The swap_lock used by sbitmap has a chain with locks taken from softirq, but the swap_lock is not protected from being preempted by softirqs.
A chain exists of:
sbq->ws[i].wait -> dispatch_wait_lock -> swap_lock
Where the sbq->ws[i].wait lock can be taken from softirq context, which means all locks below it in the chain must also be protected from softirqs.
Cc: stable@vger.kernel.org Reported-by: Clark Williams <williams@redhat.com> Fixes: 58ab5e32e6fd ("sbitmap: silence bogus lockdep IRQ warning") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 65c2d06250a6..864354000e04 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -26,14 +26,9 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) { unsigned long mask, val; - unsigned long __maybe_unused flags; bool ret = false; - /* Silence bogus lockdep warning */ -#if defined(CONFIG_LOCKDEP) - local_irq_save(flags); -#endif - spin_lock(&sb->map[index].swap_lock); + spin_lock_bh(&sb->map[index].swap_lock); if (!sb->map[index].cleared) goto out_unlock; @@ -54,10 +49,7 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) ret = true; out_unlock: - spin_unlock(&sb->map[index].swap_lock); -#if defined(CONFIG_LOCKDEP) - local_irq_restore(flags); -#endif + spin_unlock_bh(&sb->map[index].swap_lock); return ret; }
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