From: Peter Zijlstra <peterz@infradead.org> To: Byungchul Park <byungchul.park@lge.com> Cc: mingo@kernel.org, tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, npiggin@gmail.com Subject: Re: [PATCH v5 06/13] lockdep: Implement crossrelease feature Date: Tue, 28 Feb 2017 19:15:47 +0100 [thread overview] Message-ID: <20170228181547.GM5680@worktop> (raw) In-Reply-To: <1484745459-2055-7-git-send-email-byungchul.park@lge.com> On Wed, Jan 18, 2017 at 10:17:32PM +0900, Byungchul Park wrote: > + /* > + * Each work of workqueue might run in a different context, > + * thanks to concurrency support of workqueue. So we have to > + * distinguish each work to avoid false positive. > + * > + * TODO: We can also add dependencies between two acquisitions > + * of different work_id, if they don't cause a sleep so make > + * the worker stalled. > + */ > + unsigned int work_id; > +/* > + * Crossrelease needs to distinguish each work of workqueues. > + * Caller is supposed to be a worker. > + */ > +void crossrelease_work_start(void) > +{ > + if (current->xhlocks) > + current->work_id++; > +} So what you're trying to do with that 'work_id' thing is basically wipe the entire history when we're at the bottom of a context. Which is a useful operation, but should arguably also be done on the return to userspace path. Any historical lock from before the current syscall is irrelevant. (And we should not be returning to userspace with locks held anyway -- lockdep already has a check for that).
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: Byungchul Park <byungchul.park@lge.com> Cc: mingo@kernel.org, tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, npiggin@gmail.com Subject: Re: [PATCH v5 06/13] lockdep: Implement crossrelease feature Date: Tue, 28 Feb 2017 19:15:47 +0100 [thread overview] Message-ID: <20170228181547.GM5680@worktop> (raw) In-Reply-To: <1484745459-2055-7-git-send-email-byungchul.park@lge.com> On Wed, Jan 18, 2017 at 10:17:32PM +0900, Byungchul Park wrote: > + /* > + * Each work of workqueue might run in a different context, > + * thanks to concurrency support of workqueue. So we have to > + * distinguish each work to avoid false positive. > + * > + * TODO: We can also add dependencies between two acquisitions > + * of different work_id, if they don't cause a sleep so make > + * the worker stalled. > + */ > + unsigned int work_id; > +/* > + * Crossrelease needs to distinguish each work of workqueues. > + * Caller is supposed to be a worker. > + */ > +void crossrelease_work_start(void) > +{ > + if (current->xhlocks) > + current->work_id++; > +} So what you're trying to do with that 'work_id' thing is basically wipe the entire history when we're at the bottom of a context. Which is a useful operation, but should arguably also be done on the return to userspace path. Any historical lock from before the current syscall is irrelevant. (And we should not be returning to userspace with locks held anyway -- lockdep already has a check for that). -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-02-28 19:44 UTC|newest] Thread overview: 124+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-01-18 13:17 [PATCH v5 00/13] lockdep: Implement crossrelease feature Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 01/13] lockdep: Refactor lookup_chain_cache() Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-19 9:16 ` Boqun Feng 2017-01-19 9:52 ` Byungchul Park 2017-01-19 9:52 ` Byungchul Park 2017-01-26 7:53 ` Byungchul Park 2017-01-26 7:53 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 02/13] lockdep: Fix wrong condition to print bug msgs for MAX_LOCKDEP_CHAIN_HLOCKS Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 03/13] lockdep: Add a function building a chain between two classes Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 04/13] lockdep: Refactor save_trace() Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 05/13] lockdep: Pass a callback arg to check_prev_add() to handle stack_trace Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-26 7:43 ` Byungchul Park 2017-01-26 7:43 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 06/13] lockdep: Implement crossrelease feature Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-02-28 12:26 ` Peter Zijlstra 2017-02-28 12:26 ` Peter Zijlstra 2017-02-28 12:45 ` Peter Zijlstra 2017-02-28 12:45 ` Peter Zijlstra 2017-02-28 12:49 ` Peter Zijlstra 2017-02-28 12:49 ` Peter Zijlstra 2017-03-01 6:20 ` Byungchul Park 2017-03-01 6:20 ` Byungchul Park 2017-02-28 13:05 ` Peter Zijlstra 2017-02-28 13:05 ` Peter Zijlstra 2017-02-28 13:28 ` Byungchul Park 2017-02-28 13:28 ` Byungchul Park 2017-02-28 13:35 ` Peter Zijlstra 2017-02-28 13:35 ` Peter Zijlstra 2017-02-28 14:00 ` Byungchul Park 2017-02-28 14:00 ` Byungchul Park 2017-02-28 13:10 ` Peter Zijlstra 2017-02-28 13:10 ` Peter Zijlstra 2017-02-28 13:24 ` Byungchul Park 2017-02-28 13:24 ` Byungchul Park 2017-02-28 18:29 ` Peter Zijlstra 2017-02-28 18:29 ` Peter Zijlstra 2017-03-01 4:40 ` Byungchul Park 2017-03-01 4:40 ` Byungchul Park 2017-03-01 10:45 ` Peter Zijlstra 2017-03-01 10:45 ` Peter Zijlstra 2017-03-01 12:10 ` Byungchul Park 2017-03-01 12:10 ` Byungchul Park 2017-02-28 13:40 ` Peter Zijlstra 2017-02-28 13:40 ` Peter Zijlstra 2017-03-01 5:43 ` Byungchul Park 2017-03-01 5:43 ` Byungchul Park 2017-03-01 12:28 ` Peter Zijlstra 2017-03-01 12:28 ` Peter Zijlstra 2017-03-02 13:40 ` Peter Zijlstra 2017-03-02 13:40 ` Peter Zijlstra 2017-03-03 0:17 ` Byungchul Park 2017-03-03 0:17 ` Byungchul Park 2017-03-03 8:14 ` Peter Zijlstra 2017-03-03 8:14 ` Peter Zijlstra 2017-03-03 9:13 ` Peter Zijlstra 2017-03-03 9:13 ` Peter Zijlstra 2017-03-03 9:32 ` Peter Zijlstra 2017-03-03 9:32 ` Peter Zijlstra 2017-03-05 3:33 ` Byungchul Park 2017-03-05 3:33 ` Byungchul Park 2017-08-10 12:18 ` [tip:locking/core] locking/lockdep: Avoid creating redundant links tip-bot for Peter Zijlstra 2017-03-05 3:08 ` [PATCH v5 06/13] lockdep: Implement crossrelease feature Byungchul Park 2017-03-05 3:08 ` Byungchul Park 2017-03-07 11:42 ` Peter Zijlstra 2017-03-07 11:42 ` Peter Zijlstra 2017-03-03 0:39 ` Byungchul Park 2017-03-03 0:39 ` Byungchul Park 2017-02-28 15:49 ` Peter Zijlstra 2017-02-28 15:49 ` Peter Zijlstra 2017-03-01 5:17 ` Byungchul Park 2017-03-01 5:17 ` Byungchul Park 2017-03-01 6:18 ` Byungchul Park 2017-03-01 6:18 ` Byungchul Park 2017-03-02 2:52 ` Byungchul Park 2017-03-02 2:52 ` Byungchul Park 2017-02-28 18:15 ` Peter Zijlstra [this message] 2017-02-28 18:15 ` Peter Zijlstra 2017-03-01 7:21 ` Byungchul Park 2017-03-01 7:21 ` Byungchul Park 2017-03-01 10:43 ` Peter Zijlstra 2017-03-01 10:43 ` Peter Zijlstra 2017-03-01 12:27 ` Byungchul Park 2017-03-01 12:27 ` Byungchul Park 2017-03-02 4:20 ` Matthew Wilcox 2017-03-02 4:20 ` Matthew Wilcox 2017-03-02 4:45 ` byungchul.park 2017-03-02 4:45 ` byungchul.park 2017-03-02 14:39 ` Matthew Wilcox 2017-03-02 14:39 ` Matthew Wilcox 2017-03-02 23:50 ` Byungchul Park 2017-03-02 23:50 ` Byungchul Park 2017-03-05 8:01 ` Byungchul Park 2017-03-05 8:01 ` Byungchul Park 2017-03-14 7:36 ` Byungchul Park 2017-03-14 7:36 ` Byungchul Park 2017-03-02 13:41 ` Peter Zijlstra 2017-03-02 13:41 ` Peter Zijlstra 2017-03-02 23:43 ` Byungchul Park 2017-03-02 23:43 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 07/13] lockdep: Make print_circular_bug() aware of crossrelease Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 08/13] lockdep: Apply crossrelease to completions Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 09/13] pagemap.h: Remove trailing white space Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 10/13] lockdep: Apply crossrelease to PG_locked locks Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 11/13] lockdep: Apply lock_acquire(release) on __Set(__Clear)PageLocked Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 12/13] lockdep: Move data of CONFIG_LOCKDEP_PAGELOCK from page to page_ext Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-18 13:17 ` [PATCH v5 13/13] lockdep: Crossrelease feature documentation Byungchul Park 2017-01-18 13:17 ` Byungchul Park 2017-01-20 9:08 ` [REVISED DOCUMENT] " Byungchul Park 2017-01-20 9:08 ` Byungchul Park 2017-02-20 8:38 ` [PATCH v5 00/13] lockdep: Implement crossrelease feature Byungchul Park 2017-02-20 8:38 ` Byungchul Park
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