Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754201AbYFJPe1 (ORCPT ); Tue, 10 Jun 2008 11:34:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751714AbYFJPeS (ORCPT ); Tue, 10 Jun 2008 11:34:18 -0400 Received: from g5t0009.atlanta.hp.com ([15.192.0.46]:4481 "EHLO g5t0009.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751559AbYFJPeQ (ORCPT ); Tue, 10 Jun 2008 11:34:16 -0400 Subject: Re: 2.6.26-rc5-mm2 From: Lee Schermerhorn To: Nick Piggin Cc: Andrew Morton , linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org, linux-mm@kvack.org In-Reply-To: <200806101728.27486.nickpiggin@yahoo.com.au> References: <20080609223145.5c9a2878.akpm@linux-foundation.org> <200806101728.27486.nickpiggin@yahoo.com.au> Content-Type: text/plain Organization: HP/OSLO Date: Tue, 10 Jun 2008 11:34:25 -0400 Message-Id: <1213112065.6872.12.camel@lts-notebook> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4113 Lines: 86 On Tue, 2008-06-10 at 17:28 +1000, Nick Piggin wrote: > On Tuesday 10 June 2008 15:31, Andrew Morton wrote: > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.26-rc5/2. > >6.26-rc5-mm2/ > > > > BTW. would be trying to test this more myself, but last mm I based the > lockless patches on didn't boot, and this one dies pretty quickly when > you try to get into reclaim: > > ------------[ cut here ]------------ > kernel BUG at mm/swap_state.c:77! > invalid opcode: 0000 [1] SMP DEBUG_PAGEALLOC > last sysfs file: /sys/devices/system/cpu/cpu7/cache/index2/shared_cpu_map > CPU 7 > Modules linked in: > Pid: 13550, comm: sh Not tainted 2.6.26-rc5-mm2-dirty #412 > RIP: 0010:[] [] > add_to_swap_cache+0xd9/0x120 > RSP: 0018:ffff81010c62d8a8 EFLAGS: 00010246 > RAX: 2000000000020009 RBX: ffffe2000107da88 RCX: c000000000000000 > RDX: 0000000000000020 RSI: 000000000000eea2 RDI: ffffe2000107da88 > RBP: ffff81010c62d8c8 R08: fffffffffa48016e R09: 0000000000000000 > R10: ffffffff80857fa0 R11: 2222222222222222 R12: ffff81012e126520 > R13: 000000000000eea2 R14: ffff8100727bea20 R15: ffff81010c62d9b8 > FS: 00002b5b33cafdc0(0000) GS:ffff81012ff07800(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > CR2: 000000000175e280 CR3: 000000012e292000 CR4: 00000000000006e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > Process sh (pid: 13550, threadinfo ffff81010c62c000, task ffff810116b01110) > Stack: ffff81010c62d8c8 ffffe2000107da88 ffff81012e126520 ffff81012e126400 > ffff81010c62d908 ffffffff80292851 000000000000eea2 ffff81012e126708 > ffffe2000107da88 ffffffff80701420 ffff81010c62db68 ffff81010c62dc88 > Call Trace: > [] shmem_writepage+0x121/0x200 > [] shrink_page_list+0x559/0x6b0 > [] shrink_list+0x21c/0x520 > [] ? determine_dirtyable_memory+0x15/0x30 > [] ? get_dirty_limits+0x22/0x2a0 > [] shrink_zone+0x241/0x330 > [] try_to_free_pages+0x237/0x3a0 > [] ? isolate_pages_global+0x0/0x270 > [] __alloc_pages_internal+0x206/0x4b0 > [] alloc_pages_current+0x87/0xd0 > [] __get_free_pages+0xe/0x60 > [] copy_process+0xba/0x1240 > [] do_fork+0x82/0x2a0 > [] ? trace_hardirqs_on+0xd/0x10 > [] ? _spin_unlock_irq+0x2b/0x40 > [] ? trace_hardirqs_on_thunk+0x3a/0x3f > [] ? system_call_after_swapgs+0x7b/0x80 > [] sys_clone+0x23/0x30 > > The tmpfs PageSwapBacked stuff seems rather broken. For > them write_begin/write_end path, it is filemap.c, not shmem.c, > which allocates the page, so its no wonder it goes bug. Will > try to do more testing without shmem. > > Also, just noticed > mm/memory.c:do_wp_page > //TODO: is this safe? do_anonymous_page() does it this way. > > That's a bit disheartening. Surely a question like that has to > be answered definitively? (hopefully whatever is doing the > asking won't get merged until answered) I put those C++ TODO comments in there specifically to raise their visibility in hopes that someone [like you :)] would notice and maybe have an answer to the question. I noted the issue in the change log as well--i.e., that I had moved set_pte_at() to after the lru_cache_add and 'new_rmap. The existing order may be that way for a reason, but it's not clear [to me] what that reason is. As I noted, do_anonymous_page() sets the pte after the lru_add and new_rmap. I agree, these questions need to be answered and the TODO's resolved before merging. Any thoughts as to the ordering? Lee -- 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/