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Date: Thu, 18 Feb 2016 10:57:21 +0100 From: Thomas.Betker@...de-schwarz.com To: David Woodhouse <dwmw2@...radead.org> Cc: computersforpeace@...il.com, Artem Bityutskiy <dedekind1@...il.com>, Deng Chao <deng.chao1@....com.cn>, Joakim Tjernlund <Joakim.Tjernlund@...inera.com>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>, linux-mtd <linux-mtd-bounces@...ts.infradead.org>, Ming Liu <liu.ming50@...il.com>, "sztomi89@...il.com" <sztomi89@...il.com>, Alexander Viro <viro@...iv.linux.org.uk>, wangzaiwei <wangzaiwei@...-vision.cn> Subject: Re: JFFS2 deadlock Hello David: > > Please could you try what's in the tree at > > http://git.infradead.org/users/dwmw2/jffs2-fixes.git > Your patch looks much simpler, and I will definitely test it. It may > take a few days, though, as I have to unearth the test scripts, and > find a time slot for testing. Here is what I did (sorry for the wait, things were piling up): 1) Removed Deng Chao's patch from my kernel, added your patch "jffs2: Fix page lock / f->sem deadlock". I am still on linux-3.14, but jffs2 hasn't changed much since then, so this shouldn't make a difference. Added a printk() before mutex_unlock(&f->sem) to check if the prospective page was locked, i.e. if the deadlock situation actually occurs. 2) On my target system, started wangzaiwei's test (with some fixes), plus a loop copying a large file over and over (to get GC rolling, which increases the chance of a deadlock). 3) After 24 hours, the system was still alive, and the printk() had been hit 32 times. So yes, I am confident that your patch avoids the deadlock, and if that's good enough for you, please add my Tested-by:. However, I am going to run some more stress tests here just to check that there weren't any unexpected side effects. (Don't get me wrong -- I am sure the patch is fine, but for me it's a case of "once bitten, twice shy" ...) Best regards, Thomas Betker
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