From: Qian Cai <email@example.com> To: Marco Elver <firstname.lastname@example.org> Cc: Peter Zijlstra <email@example.com>, Will Deacon <firstname.lastname@example.org>, Ingo Molnar <email@example.com>, Linux Kernel Mailing List <firstname.lastname@example.org>, "paul E. McKenney" <email@example.com>, kasan-dev <firstname.lastname@example.org> Subject: Re: [PATCH] locking/osq_lock: fix a data race in osq_wait_next Date: Tue, 28 Jan 2020 07:53:00 -0500 Message-ID: <C50F23AD-7CCA-423B-9C13-E06596CB4399@lca.pw> (raw) In-Reply-To: <CANpmjNNo6yW-y-Af7JgvWi3t==+=02hE4-pFU4OiH8yvbT3Byg@mail.gmail.com> > On Jan 28, 2020, at 6:46 AM, Marco Elver <email@example.com> wrote: > > Qian: firstly I suggest you try > CONFIG_KCSAN_REPORT_ONCE_IN_MS=1000000000 as mentioned before so your > system doesn't get spammed, considering you do not use the default > config but want to use all debugging tools at once which seems to > trigger certain data races more than usual. Yes, I had that. There are still many reports that I plan to look at them one by one. It takes so much time that cause systemd storage lookup timeouts and I needed to manually get out of the emergency shell. > > Secondly, what are your expectations? If you expect the situation to > be perfect tomorrow, you'll be disappointed. This is inherent, given > the problem we face (safe concurrency). Consider the various parts to > this story: concurrent kernel code, the LKMM, people's preferences and > opinions, and KCSAN (which is late to the party). All of them are > still evolving, hopefully together. At least that's my expectation. I’ll try to reduce splats as many as possible by any data_race(), disable the whole file or actually fix it. Any resolved splat will hurt the ability to find the real data races at some degrees. > > What to do about osq_lock here? If people agree that no further > annotations are wanted, and the reasoning above concludes there are no > bugs, we can blacklist the file. That would, however, miss new data > races in future. This is a question to locking maintainers. data_race() macro sounds reasonable to me, but blacklisted the file is still better than leaving it as-is.
next prev parent reply index Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-01-22 16:38 Qian Cai 2020-01-22 16:59 ` Will Deacon 2020-01-22 17:08 ` Qian Cai 2020-01-22 22:38 ` Marco Elver 2020-01-22 23:54 ` Qian Cai 2020-01-23 9:39 ` Peter Zijlstra 2020-01-28 3:11 ` Qian Cai 2020-01-28 11:46 ` Marco Elver 2020-01-28 12:53 ` Qian Cai [this message] 2020-01-28 16:52 ` Peter Zijlstra 2020-01-28 16:56 ` Peter Zijlstra 2020-01-29 0:22 ` Paul E. McKenney 2020-01-29 15:29 ` Marco Elver 2020-01-29 18:40 ` Peter Zijlstra 2020-01-30 13:39 ` Marco Elver 2020-01-30 13:48 ` Peter Zijlstra 2020-01-31 3:32 ` Qian Cai 2020-01-29 18:49 ` Peter Zijlstra 2020-01-29 19:26 ` Paul E. McKenney 2020-01-23 9:36 ` Peter Zijlstra 2020-01-28 3:12 ` Qian Cai 2020-01-28 8:18 ` Marco Elver 2020-01-28 10:10 ` Qian Cai 2020-01-28 10:29 ` Marco Elver 2020-01-22 17:09 ` Peter Zijlstra
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