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Date: Sat, 24 Aug 2013 06:50:45 -0400 From: Peter Hurley <peter@...leysoftware.com> To: Andy Lutomirski <luto@...capital.net> CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: Finding out who's holding a lock? On 08/22/2013 08:52 PM, Andy Lutomirski wrote: > My program is occasionally seeing slow page faults. latencytop says > they're slow because they're waiting for read access to mmap_sem, but > latencytop isn't showing any other thread in the process blocking. > > Is there any straightforward way to find out who called down_write on > mmap_sem when down_read is slow? Build with CONFIG_LOCKDEP (Kernel Debugging -> Lock Debugging -> "Lock Debugging: prove locking correctness"). When you experience the slowdown, sysrq + d (displays all currently held locks). sysrq can also be programmatically triggered with "echo d > /proc/sysrq-trigger" or equivalent. Regards, Peter Hurley -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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