Messages in this thread | | | From | Nick Piggin <> | Subject | Re: Lockless/Get_User_Pages_Fast causes Xorg 1.4.99.* to lock | Date | Mon, 7 Jul 2008 17:01:56 +1000 |
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On Saturday 05 July 2008 06:29, Hugh Dickins wrote: > 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: [<ffffffff80297e30>] > > 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] [<ffffffff80239a9b>] dup_mm+0x26b/0x3c0 > > [ 269.224507] [<ffffffff8023a84c>] copy_process+0xc2c/0x1210 > > [ 269.224518] [<ffffffff8023aea3>] do_fork+0x73/0x310 > > [ 269.224526] [<ffffffff8024719e>] sys_rt_sigaction+0x8e/0xd0 > > [ 269.224536] [<ffffffff8020c2db>] system_call_after_swapgs+0x7b/0x80 > > [ 269.224542] [<ffffffff8020c5d7>] 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 <hugh@veritas.com>
(back from vaccation)
Great, thanks Hugh. Always nice to read the fix before the bug report :) powerpc should need it too, as well as an equivalent for s390.
Thanks, Nick
> --- > 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)
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