Messages in this thread |  | | Subject | Re: Linux 2.5.69 | From | Steven Cole <> | Date | 05 May 2003 10:16:07 -0600 |
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On Mon, 2003-05-05 at 09:56, Linus Torvalds wrote: > [ Linux-kernel added to the cc, since I got several queries about what the > crashes were.. ] > > On Mon, 5 May 2003, David van Hoose wrote: > > > > Can I get some details regarding the AGP problem? I had some really bad > > random crashes, panics, and hardlocks up through 2.5.68, and I'm > > wondering if this is the same issue. I first noticed them around 2.5.63. > > They actually started in 2.5.60 if it's the same bug. > > And yes, you'd get random crashes, panics, lockups and even reboots. The > problem was that the pmd/pgd's were put in the slab cache in between > 2.5.59 and 2.5.60, and that was simply wrong because the AGP code changes > the cacheability of the kernel pages when it maps stuff into the AGP > aperture. That in turn will change the page tables but it won't update the > cached entries in the pmd slab caches. > > So what happens is that once you exit X, and the page tables are put back > together without the cacheability changes, and you start a new program, > that program may get a page table with partly bogus kernel page table > entries. > > That, in turn, when it happens will cause _major_ memory corruption, and > your machine is toast, often in very interesting ways because the internal > kernel data structures got corrupted. It can also cause random SIGSEGV's > etc. > > But it only happens with AGP, and a lot of people either don't use it or > run only one X session. > > Linus
This fixes a problem I reported here: http://marc.theaimsgroup.com/?l=linux-kernel&m=104990441203933&w=2
Thanks, Steven
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