Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754860Ab0DUXBa (ORCPT ); Wed, 21 Apr 2010 19:01:30 -0400 Received: from mail-gw0-f46.google.com ([74.125.83.46]:65062 "EHLO mail-gw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753415Ab0DUXB2 convert rfc822-to-8bit (ORCPT ); Wed, 21 Apr 2010 19:01:28 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=fo/Tx3TwvkMoMIVn/wLaTRjdNMo2uon+zBW6h8mE7pOFhyqWe/EhJ9Y9QLA4C2NSGf VJV2a0ja/WV1v/oR65E25Hn1gU+TzpnmR8prC4K6YCOXhGwVN2wrXBds6ew5fM6ja0D2 1zhsjaR9YOHhza/2Sis5zR1s7k63eRtF1pdPA= MIME-Version: 1.0 In-Reply-To: <1271868724.2100.169.camel@barrios-desktop> References: <201004152210.o3FMA7KV001909@imap1.linux-foundation.org> <20100419190133.50a13021.kamezawa.hiroyu@jp.fujitsu.com> <20100419181442.GA19264@csn.ul.ie> <20100419193919.GB19264@csn.ul.ie> <20100421172838.0377e0cc.kamezawa.hiroyu@jp.fujitsu.com> <20100421184806.2c3ecc87.kamezawa.hiroyu@jp.fujitsu.com> <20100421102039.GG30306@csn.ul.ie> <1271868724.2100.169.camel@barrios-desktop> Date: Thu, 22 Apr 2010 08:01:27 +0900 Message-ID: Subject: Re: error at compaction (Re: mmotm 2010-04-15-14-42 uploaded From: Minchan Kim To: Mel Gorman Cc: KAMEZAWA Hiroyuki , linux-kernel@vger.kernel.org, akpm@linux-foundation.org, "linux-mm@kvack.org" , "kosaki.motohiro@jp.fujitsu.com" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8320 Lines: 151 On Thu, Apr 22, 2010 at 1:52 AM, Minchan Kim wrote: > Hi, Mel. > > On Wed, 2010-04-21 at 11:20 +0100, Mel Gorman wrote: >> On Wed, Apr 21, 2010 at 06:48:06PM +0900, KAMEZAWA Hiroyuki wrote: >> > On Wed, 21 Apr 2010 17:28:38 +0900 >> > KAMEZAWA Hiroyuki wrote: >> > >> > > On Mon, 19 Apr 2010 20:39:19 +0100 >> > > Mel Gorman wrote: >> > > >> > > > On Mon, Apr 19, 2010 at 07:14:42PM +0100, Mel Gorman wrote: >> > > > ==== CUT HERE ==== >> > > > mm,compaction: Map free pages in the address space after they get split for compaction >> > > > >> > > > split_free_page() is a helper function which takes a free page from the >> > > > buddy lists and splits it into order-0 pages. It is used by memory >> > > > compaction to build a list of destination pages. If >> > > > CONFIG_DEBUG_PAGEALLOC is set, a kernel paging request bug is triggered >> > > > because split_free_page() did not call the arch-allocation hooks or map >> > > > the page into the kernel address space. >> > > > >> > > > This patch does not update split_free_page() as it is called with >> > > > interrupts held. Instead it documents that callers of split_free_page() >> > > > are responsible for calling the arch hooks and to map the page and fixes >> > > > compaction. >> > > > >> > > > This is a fix to the patch mm-compaction-memory-compaction-core.patch. >> > > > >> > > > Signed-off-by: Mel Gorman >> > > >> > > Sorry, I think I hit another? error again. (sorry, no log.) >> > > What I did was... >> > >    Running 2 shells. >> > >    while true; do make -j 16;make cleanl;done >> > >    and >> > >    while true; do echo 0 > /proc/sys/vm/compact_memory;done >> > > >> > > >> > > Using the same config. >> > > >> > > Apr 21 17:27:47 localhost kernel: ------------[ cut here ]------------ >> > > Apr 21 17:27:47 localhost kernel: kernel BUG at include/linux/swapops.h:105! >> > > Apr 21 17:27:47 localhost kernel: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC >> > > Apr 21 17:27:47 localhost kernel: last sysfs file: /sys/devices/virtual/net/br0/statistics/collisions >> > > Apr 21 17:27:47 localhost kernel: CPU 3 >> > > Apr 21 17:27:47 localhost kernel: Modules linked in: fuse sit tunnel4 ipt_MASQUERADE iptable_nat nf_nat bridge stp llc sunrpc cpufreq_ondemand acpi_cpufreq freq_table mperf xt_physdev ip6t_REJECT nf_conntrack_ipv6 ip6table_filter ip6_tables ipv6 dm_multipath uinput ioatdma ppdev parport_pc i5000_edac bnx2 iTCO_wdt edac_core iTCO_vendor_support shpchp parport e1000e kvm_intel dca kvm i2c_i801 i2c_core i5k_amb pcspkr megaraid_sas [last unloaded: microcode] >> > > Apr 21 17:27:47 localhost kernel: >> > > Apr 21 17:27:47 localhost kernel: Pid: 27892, comm: cc1 Tainted: G        W   2.6.34-rc4-mm1+ #4 D2519/PRIMERGY >> > > Apr 21 17:27:47 localhost kernel: RIP: 0010:[]  [] migration_entry_wait+0x16f/0x180 >> > > Apr 21 17:27:47 localhost kernel: RSP: 0000:ffff88008d9efe08  EFLAGS: 00010246 >> > > Apr 21 17:27:47 localhost kernel: RAX: ffffea0000000000 RBX: ffffea0000241100 RCX: 0000000000000001 >> > > Apr 21 17:27:47 localhost kernel: RDX: 000000000000a4e0 RSI: ffff880621a4ab00 RDI: 000000000149c03e >> > > Apr 21 17:27:47 localhost kernel: RBP: ffff88008d9efe38 R08: 0000000000000000 R09: 0000000000000000 >> > > Apr 21 17:27:47 localhost kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff880621a4aae8 >> > > Apr 21 17:27:47 localhost kernel: R13: 00000000bf811000 R14: 000000000149c03e R15: 0000000000000000 >> > > Apr 21 17:27:47 localhost kernel: FS:  00007fe6abc90700(0000) GS:ffff880005a00000(0000) knlGS:0000000000000000 >> > > Apr 21 17:27:47 localhost kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> > > Apr 21 17:27:47 localhost kernel: CR2: 00007fe6a37279a0 CR3: 000000008d942000 CR4: 00000000000006e0 >> > > Apr 21 17:27:47 localhost kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> > > Apr 21 17:27:47 localhost kernel: DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 >> > > Apr 21 17:27:47 localhost kernel: Process cc1 (pid: 27892, threadinfo ffff88008d9ee000, task ffff8800b23ec820) >> > > Apr 21 17:27:47 localhost kernel: Stack: >> > > Apr 21 17:27:47 localhost kernel: ffffea000101aee8 ffff880621a4aae8 ffff88008d9efe38 00007fe6a37279a0 >> > > Apr 21 17:27:47 localhost kernel: <0> ffff8805d9706d90 ffff880621a4aa00 ffff88008d9efef8 ffffffff81126d05 >> > > Apr 21 17:27:47 localhost kernel: <0> ffff88008d9efec8 0000000000000246 0000000000000000 ffffffff81586533 >> > > Apr 21 17:27:47 localhost kernel: Call Trace: >> > > Apr 21 17:27:47 localhost kernel: [] handle_mm_fault+0x995/0x9b0 >> > > Apr 21 17:27:47 localhost kernel: [] ? do_page_fault+0x103/0x330 >> > > Apr 21 17:27:47 localhost kernel: [] ? finish_task_switch+0x0/0xf0 >> > > Apr 21 17:27:47 localhost kernel: [] do_page_fault+0x16e/0x330 >> > > Apr 21 17:27:47 localhost kernel: [] page_fault+0x25/0x30 >> > > Apr 21 17:27:47 localhost kernel: Code: 53 08 85 c9 0f 84 32 ff ff ff 8d 41 01 89 4d d8 89 45 d4 8b 75 d4 8b 45 d8 f0 0f b1 32 89 45 dc 8b 45 dc 39 c8 74 aa 89 c1 eb d7 <0f> 0b eb fe 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 >> > > Apr 21 17:27:47 localhost kernel: RIP  [] migration_entry_wait+0x16f/0x180 >> > > Apr 21 17:27:47 localhost kernel: RSP >> > > Apr 21 17:27:47 localhost kernel: ---[ end trace 4860ab585c1fcddb ]--- >> > > >> > >> > It seems that this is a new error. >> > >> > >> > static inline struct page *migration_entry_to_page(swp_entry_t entry) >> > { >> >         struct page *p = pfn_to_page(swp_offset(entry)); >> >         /* >> >          * Any use of migration entries may only occur while the >> >          * corresponding page is locked >> >          */ >> >         BUG_ON(!PageLocked(p)); >> >         return p; >> > } >> > >> > >> > Hits this BUG_ON()....then, the page migration_entry points to is unlocked. >> > >> > But we always do >> > >> >     lock_page(old_page); >> >     unamp(old_page); >> >     remap(new_page); >> >     unlock_page(old_page); >> > >> > So....some pte wasn't updated at remap ? >> > >> >> I'm working on reproducing the problem. I've hit it only once. My stress >> tests were using dd instead of make like yours did and my >> compilation-orientated test would not have been hitting compaction as >> hard. >> >> The theory I'm working on is that it's a PageSwapCache page that was >> unmapped and not remapped (remap_swapcache == 0) in move_to_new_page(). >> In this case, the page would be migrated, left in place and unlocked. >> Later when a swap fault occurred, the migration PTE is found and the >> bug_on triggers i.e. the bug check is no longer valid because it is >> possible for an unlocked migration pte to be left behind. > > Hmm. How about the situation? > > > CPU A                                           CPU B > > 1. unmap_and_move > 2. lock_page > 3. PageAnon && !page_mapped && PageSwapCache    3' do_fork > 4. remap_swapcache = 0                          4' pte lock, page_dup_rmap <- race happens > 5. try_to_unmap - make migration entry by 4' > 6. move_to_newpage > 7. don't call remove_migration due to 4 >                                                8. do_swap_page >                                                9. migration_entry_wait >                                                10. goto out >                                                11. fault! > > In this case, process of CPU B will be killed although it passes PageLocked > So I think we have to find another method. > > I might be wrong since nearly falling asleep. :( Yes. I was wrong. I seem to miss detach_vma before unmap_region. Sorry, Ignore this, please. :( -- Kind regards, Minchan Kim -- 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/