From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 30 Jul 2007 18:39:12 -0400 Subject: Re: [patch][rfc] remove ZERO_PAGE? Message-ID: <20070730223912.GM2386@fieldses.org> References: <20070727021943.GD13939@wotan.suse.de> <20070730115751.a2aaa28f.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070730115751.a2aaa28f.akpm@linux-foundation.org> From: "J. Bruce Fields" Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: "Luiz Fernando N. Capitulino" , Nick Piggin , Linus Torvalds , Hugh Dickins , Andrea Arcangeli , Linux Memory Management List , lcapitulino@mandriva.com.br, Neil Brown List-ID: On Mon, Jul 30, 2007 at 11:57:51AM -0700, Andrew Morton wrote: > On Mon, 30 Jul 2007 10:52:27 -0300 > "Luiz Fernando N. Capitulino" wrote: > > > Hi Nick, > > > > On 7/26/07, Nick Piggin wrote: > > > > > I'd like to see if we can get the ball rolling on this again, and try to > > > get it in 2.6.24 maybe. Any comments? > > > > I'm trying this patch and got this during the weekend (gmail will > > probably break lines automatically, grrr): > > > > """ > > [29711.081281] BUG: unable to handle kernel NULL pointer dereference > > at virtual address 00000004 > > [29711.081300] printing eip: > > [29711.081305] dcb5aa49 > > [29711.081308] *pde = 00000000 > > [29711.081315] Oops: 0000 [#1] > > [29711.081319] SMP > > [29711.081325] Modules linked in: nfsd exportfs auth_rpcgss nfs lockd > > nfs_acl sunrpc capability commoncap af_packet ipv6 ide_cd ide_core > > binfmt_misc loop dm_mod floppy pcspkr snd_pcm_oss snd_mixer_oss > > snd_via82xx gameport snd_ac97_codec i2c_viapro amd64_agp snd_pcm > > snd_timer ac97_bus snd_page_alloc snd_mpu401_uart snd_rawmidi > > snd_seq_device snd agpgart ehci_hcd uhci_hcd i2c_core via_rhine k8temp > > mii usbcore evdev tsdev soundcore sr_mod sg ext3 jbd sd_mod pata_via > > sata_via libata scsi_mod > > [29711.081445] CPU: 0 > > [29711.081446] EIP: 0060:[] Not tainted VLI > > [29711.081447] EFLAGS: 00010246 (2.6.23-rc1-zpage #1) > > [29711.081511] EIP is at encode_fsid+0x89/0xb0 [nfsd] > > [29711.081529] eax: d99f4000 ebx: d80af064 ecx: 00000000 edx: 00000002 > > [29711.081549] esi: d809204c edi: d80af14c ebp: d8788f04 esp: d8788efc > > [29711.081569] ds: 007b es: 007b fs: 00d8 gs: 0000 ss: 0068 > > [29711.081589] Process nfsd (pid: 3474, ti=d8788000 task=dac07740 > > task.ti=d8788000) > > [29711.081609] Stack: 00000000 d809203c d8788f28 dcb5ab25 d80af064 > > c0945160 dcb59202 00000000 > > [29711.081644] d80b0000 dcb5bf90 dcb77404 d8788f38 dcb5bfb3 > > d80af14c d80b0000 d8788f68 > > [29711.081679] dcb4d32c d87b4c44 d87b4a80 d8788f60 00000003 > > d8092018 d8092000 0000001c > > [29711.081714] Call Trace: > > [29711.081738] [] show_trace_log_lvl+0x1a/0x30 > > [29711.081760] [] show_stack_log_lvl+0xab/0xd0 > > [29711.081779] [] show_registers+0x1d1/0x2d0 > > [29711.081798] [] die+0x116/0x250 > > [29711.081815] [] do_page_fault+0x28b/0x690 > > [29711.081836] [] error_code+0x72/0x78 > > [29711.081856] [] encode_fattr3+0xb5/0x140 [nfsd] > > [29711.081888] [] nfs3svc_encode_attrstat+0x23/0x50 [nfsd] > > [29711.081921] [] nfsd_dispatch+0x18c/0x220 [nfsd] > > [29711.081950] [] svc_process+0x42a/0x7b0 [sunrpc] > > [29711.081985] [] nfsd+0x169/0x290 [nfsd] > > [29711.082013] [] kernel_thread_helper+0x7/0x18 > > [29711.082032] ======================= > > [29711.082047] Code: 48 30 89 cb c1 fb 1f 89 d8 0f c8 89 06 89 c8 0f > > c8 89 46 04 8d 46 08 5b 5e 5d c3 8d b4 26 00 00 00 00 8b 83 88 00 00 > > 00 8b 48 34 <8b> 51 04 33 51 0c 8b 01 33 41 08 89 d1 0f c8 0f c9 89 46 > > 04 8d > > [29711.082150] EIP: [] encode_fsid+0x89/0xb0 [nfsd] SS:ESP > > 0068:d8788efc > > """ > > > > Now I'm not sure if this was caused by your patch, or is a bug > > somewhere else. > > It's a little hard to see how Nick's patch could have caused that to > happen. > > Neil, Bruce: does this look at all familiar? Not to me. > We don't appear to have changed anything in there for months... Well, I've fooled around with the exports in 2.6.23-rc1, and Neil added the uuid stuff some time around 2.6.21. It looks to me like it's oopsing at the deference of fhp->fh_export->ex_uuid in encode_fsid(), which is exactly the case commit b41eeef14d claims to fix. Looks like that's been in since v2.6.22-rc1; what kernel is this? --b. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org