Date: Sat, 4 Jun 2016 22:02:37 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Michael Butler <imb@protected-networks.net> Cc: Matthew Macy <mmacy@nextbsd.org>, "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, alc@freebsd.org Subject: Re: repeatable panic on pageout with 945GM Message-ID: <20160604190237.GD38613@kib.kiev.ua> In-Reply-To: <88ad4228-2583-8a91-1751-d16f7a51de91@protected-networks.net> References: <2490f1c7-8153-ece3-49ed-4b3886564fd7@protected-networks.net> <da19738b-6bf1-10a3-4428-43b6095ec35a@protected-networks.net> <205d4423-b834-9a21-785f-fa15d44c78ec@protected-networks.net> <CAHM0Q_PR5Aoak6A7f=tsRy0DJFCmLDVfRGpceZ0mXU3P%2BxO8DA@mail.gmail.com> <1551419a1db.12929035f45012.326107747932338888@nextbsd.org> <939f9d2b-e925-e8e0-0ff3-8d90623728c6@protected-networks.net> <1551c5dbd86.c68532b5123717.566503881838650848@nextbsd.org> <20160604174745.GB38613@kib.kiev.ua> <88ad4228-2583-8a91-1751-d16f7a51de91@protected-networks.net>
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On Sat, Jun 04, 2016 at 02:59:01PM -0400, Michael Butler wrote: > On 06/04/16 13:47, Konstantin Belousov wrote: > > [ .. snip .. ] > > > I believe that this is a bug in amd64 pmap. Fictitious pages are not > > promoted, in particular, the pv_table array does not span over the > > dynamically registered fictitious ranges. As result, pa_to_pvh() returns > > garbage and pvh must not be accessed in the case of 'small_mappings' in > > several pmap functions. It is typically not accessed, except in case > > when we have to drop and reacquire pv lock, to avoid LOR with pmap. > > > > i386 does not have the issue, due to pvh_global_lock. > > > > Below is the supposed fix (not tested). > > [ .. snip .. ] > > Is this something I should test and, should it not introduce any other > issues, might get committed? Would be nice to test. I expect that this patch is going to be committed, after the review.
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