Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754470AbYGDU24 (ORCPT ); Fri, 4 Jul 2008 16:28:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752162AbYGDU2s (ORCPT ); Fri, 4 Jul 2008 16:28:48 -0400 Received: from extu-mxob-2.symantec.com ([216.10.194.135]:60882 "EHLO extu-mxob-2.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752061AbYGDU2r (ORCPT ); Fri, 4 Jul 2008 16:28:47 -0400 Date: Fri, 4 Jul 2008 21:29:13 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.site To: Zan Lynx cc: Ryan Hope , LKML , Nick Piggin , Andrew Morton Subject: Re: Lockless/Get_User_Pages_Fast causes Xorg 1.4.99.* to lock In-Reply-To: <486E4FD8.4010102@acm.org> Message-ID: References: <48f7fe350807032326l1d68c94l531e44c09693b989@mail.gmail.com> <486E4FD8.4010102@acm.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3544 Lines: 75 On Fri, 4 Jul 2008, Zan Lynx wrote: > Ryan Hope wrote: > > I have tested this with 2.6.26-rc5-mm3 and with 2.6.26-rc8 w/ the > > get_user_pages_fast patches from -rc5-mm3... Xorg 1.4.99.* will start > > to load but hangs at a black screen. At this point, I can not switch > > to another tty. When I try pressing ctrl+alt+del the kernel ooopses > > and the caps lock led starts to blink. This happens using the nv, > > radeon and radeonhd drivers (the nv was tested on another box > > obviously). I have also tried to unselect HAVE_GET_USER_PAGES_FAST in > > my kernel config but this does not help. I can not figure out where or > > what the bug is. I can provide any other info you guys need to figure > > this out. Let me know what I can do. > > I think that I've seen this too on 2.6.26-rc8 on my laptop. It's 64-bit Your attachment tells us it's actually 2.6.26-rc8-mm1, less of a worry. > AMD-64 single core (although I run a SMP-alternatives kernel on it) and I was > using the nv driver. > > The symptoms are the same. Everything was working great until I started X. I > SSH'd in and got the dmesg after X locked up. The full dmesg and config are > attached because Thunderbird is a very stupid program and won't let me paste > without wrapping. > > Here is a bit of what I got though. > > [ 269.224276] BUG: unable to handle kernel paging request at ffffe20003480000 > [ 269.224291] IP: [] copy_page_range+0x520/0x760 > [ 269.224306] PGD 1102067 PUD 1103067 PMD 0 > [ 269.224315] Oops: 0000 [1] SMP > > [ 269.224473] Call Trace: > [ 269.224495] [] dup_mm+0x26b/0x3c0 > [ 269.224507] [] copy_process+0xc2c/0x1210 > [ 269.224518] [] do_fork+0x73/0x310 > [ 269.224526] [] sys_rt_sigaction+0x8e/0xd0 > [ 269.224536] [] system_call_after_swapgs+0x7b/0x80 > [ 269.224542] [] ptregscall_common+0x67/0xb0 Useful info, thank you; even more useful was the Code line in your attachment > [ 269.224557] Code: 00 00 48 b9 00 00 00 00 00 e2 ff ff 48 21 d8 48 c1 e8 0c 48 8d 14 c5 00 00 00 00 48 c1 e0 06 48 29 d0 48 01 c1 0f 84 10 ff ff ff <48> 8b 01 48 89 ca f6 c4 40 74 04 48 8b 51 10 90 ff 42 08 90 ff which is enough to identify the oops as in copy_one_pte's get_page(page). Here's a patch I think we need, which I'm hoping will fix both your crashes - please let us know - thanks a lot. Stop mprotect's pte_modify from wiping out the x86 pte_special bit, which caused oops thereafter when vm_normal_page thought X's abnormal was normal. Signed-off-by: Hugh Dickins --- Fix to 2.6.26-rc8-mm1 x86-implement-pte_special.patch Perhaps something similar needed for powerpc? Nick will know. include/asm-x86/pgtable.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 2.6.26-rc8-mm1/include/asm-x86/pgtable.h 2008-07-03 11:34:55.000000000 +0100 +++ linux/include/asm-x86/pgtable.h 2008-07-04 20:58:36.000000000 +0100 @@ -57,7 +57,7 @@ /* Set of bits not changed in pte_modify */ #define _PAGE_CHG_MASK (PTE_MASK | _PAGE_PCD | _PAGE_PWT | \ - _PAGE_ACCESSED | _PAGE_DIRTY) + _PAGE_SPECIAL | _PAGE_ACCESSED | _PAGE_DIRTY) #define _PAGE_CACHE_MASK (_PAGE_PCD | _PAGE_PWT) #define _PAGE_CACHE_WB (0) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/