From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 12 Feb 2016 15:52:22 +0000 Subject: [BUG] random kernel crashes after THP rework on s390 (maybe also on PowerPC and ARM) In-Reply-To: References: <20160211192223.4b517057@thinkpad> <20160211190942.GA10244@node.shutemov.name> <20160211205702.24f0d17a@thinkpad> <20160212100137.GE25087@arm.com> Message-ID: <20160212155221.GP25087@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Feb 12, 2016 at 11:12:34AM +0100, Sebastian Ott wrote: > On Fri, 12 Feb 2016, Will Deacon wrote: > > On Thu, Feb 11, 2016 at 08:57:02PM +0100, Gerald Schaefer wrote: > > > On Thu, 11 Feb 2016 21:09:42 +0200 > > > "Kirill A. Shutemov" wrote: > > > > On Thu, Feb 11, 2016 at 07:22:23PM +0100, Gerald Schaefer wrote: > > > > > Sebastian Ott reported random kernel crashes beginning with v4.5-rc1 and > > > > > he also bisected this to commit 61f5d698 "mm: re-enable THP". Further > > > > > review of the THP rework patches, which cannot be bisected, revealed > > > > > commit fecffad "s390, thp: remove infrastructure for handling splitting PMDs" > > > > > (and also similar commits for other archs). [...] > > Do you have a reliable way to trigger the "random kernel crashes"? We've not > > seen anything reported on arm64, but I don't see why we wouldn't be affected > > by the same bug and it would be good to confirm and validate a fix. > > My testcase was compiling the kernel. Most of the time my test system > didn't survive a single compile run. During bisect I did at least 20 > compile runs to flag a commit as good. I've been building kernels all day with -rc3 on my arm64 box and haven't seen any problems yet.. :/. I'll leave it going over the weekend. Will