From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C53D2C0015E for ; Mon, 3 Jul 2023 22:06:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230427AbjGCWGF (ORCPT ); Mon, 3 Jul 2023 18:06:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35086 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229823AbjGCWGD (ORCPT ); Mon, 3 Jul 2023 18:06:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7DF7B187 for ; Mon, 3 Jul 2023 15:06:02 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 13D926103C for ; Mon, 3 Jul 2023 22:06:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1268EC433C8; Mon, 3 Jul 2023 22:06:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688421961; bh=mtkUBuCCSU5DaXd05Snv/FTvcvEwzH/oTyDXEsh8TgQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rpzDZxP2z7pNreZ6uJUSuYm1C5ID6By88inTDhUoPzotWkDQLSXinPyUicCXUmEf3 fYyEorKTYkeiJhulHHpmyk+ooTtb43A6psj6jXbeHLNGbeut+LFL2ZvC8m0J/clTyz TaOWbERkrYzKV+QZ6n8BQgOvieoE3+hLlO9GMC4lioEQhYkuSbZ9yhXNrqkHYT1sEM eAq0uq4jQv/DaYf8z7LxPNpJy8C1CjoCxSBkfhzYxCHL4YNhE+mBac3IJj2dzxOIrc 0l1HuIW0ehSDge6KVjbjbWj2XiOCNHX5P+xo2Ll38zPmKl7y2Pfh/fBxHIAEzXEEI1 TJM/WygxaLKzw== From: SeongJae Park To: Sidhartha Kumar Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, willy@infradead.org Subject: Re: [PATCH 3/4] mm/memory: convert do_shared_fault() to folios Date: Mon, 3 Jul 2023 22:05:59 +0000 Message-Id: <20230703220559.1360-1-sj@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230703055850.227169-3-sidhartha.kumar@oracle.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Sidharta, On Sun, 2 Jul 2023 22:58:49 -0700 Sidhartha Kumar wrote: > Saves three implicit calls to compound_head(). > > Signed-off-by: Sidhartha Kumar > --- > mm/memory.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index 93480e846ace6..33bf13431974c 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4594,6 +4594,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf) > { > struct vm_area_struct *vma = vmf->vma; > vm_fault_t ret, tmp; > + struct folio *folio = page_folio(vmf->page); > > ret = __do_fault(vmf); > if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) > @@ -4604,11 +4605,11 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf) > * about to become writable > */ > if (vma->vm_ops->page_mkwrite) { > - unlock_page(vmf->page); > + folio_unlock(folio); > tmp = do_page_mkwrite(vmf); > if (unlikely(!tmp || > (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { > - put_page(vmf->page); > + folio_put(folio); > return tmp; > } > } > @@ -4616,8 +4617,8 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf) > ret |= finish_fault(vmf); > if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | > VM_FAULT_RETRY))) { > - unlock_page(vmf->page); > - put_page(vmf->page); > + folio_unlock(folio); > + folio_put(folio); > return ret; > } I found the latest mm-unstable tree fails booting with stacktraces like below, and bisecting points this patch (commit a43f078c7a3b of mm-unstable). Do you have any idea? [ 7.388551] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 7.389149] systemd[1]: Starting Load Kernel Module pstore_zone... [ 7.390101] #PF: supervisor read access in kernel mode [ 7.392370] #PF: error_code(0x0000) - not-present page [ 7.392372] PGD 0 P4D 0 [ 7.392376] Oops: 0000 [#1] PREEMPT SMP PTI [ 7.392379] CPU: 9 PID: 594 Comm: systemd-journal Not tainted 6.4.0+ #8 [ S7t.a3r9t2i3n82] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-4 [ 7.392384] RIP: 0010:_compound_head (include/linux/page-flags.h:245) [ 7.400935] Code: e8 35 b5 cd ff 5d c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90f Code starting with the faulting instruction =========================================== 0: e8 35 b5 cd ff callq 0xffffffffffcdb53a 5: 5d pop %rbp 6: c3 retq 7: cc int3 8: cc int3 9: cc int3 a: cc int3 b: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1) 12: 00 00 00 00 16: 0f 1f 40 00 nopl 0x0(%rax) 1a: 90 nop 1b: 0f .byte 0xf [ 7.405283] RSP: 0000:ffffb86140cd3d58 EFLAGS: 00010202 [ 7.406551] RAX: ffff96d3c19c4d38 RBX: ffffffffa103f080 RCX: 00000001019c4067 [ 7.408233] RDX: 0000000000000000 RSI: ffff96d2c0000d38 RDI: 0000000000000000 [ 7.409893] RBP: ffffb86140cd3d90 R08: ffff96d3c19c4d38 R09: 0000000000000067 [ 7.411457] R10: 0000000000000000 R11: 00007f2ae19d5fff R12: ffffb86140cd3dd0 [ 7.412792] R13: 0000000000000001 R14: ffff96d3cb7aa450 R15: 0000000000000860 [ 7.414139] FS: 00007f2ae0f40980(0000) GS:ffff96f1fd640000(0000) knlGS:0000000000000000 [ 7.415699] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 7.416780] CR2: 0000000000000008 CR3: 0000000104830000 CR4: 00000000000006e0 [ 7.418115] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 7.419492] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 7.420830] Call Trace: [ 7.421308] [ 7.421722] ? show_regs (arch/x86/kernel/dumpstack.c:479) [ 7.422411] ? __die_body (arch/x86/kernel/dumpstack.c:421) [ 7.423113] ? __die (arch/x86/kernel/dumpstack.c:435) [ 7.423716] ? page_fault_oops (arch/x86/mm/fault.c:707) [ 7.424504] ? search_bpf_extables (kernel/bpf/core.c:751) [ 7.425329] ? __pfx__compound_head (include/linux/page-flags.h:245) [ 7.426171] ? search_exception_tables (kernel/extable.c:64) [ 7.427084] ? kernelmode_fixup_or_oops (arch/x86/mm/fault.c:762) [ 7.427995] ? __bad_area_nosemaphore (arch/x86/mm/fault.c:860) [ 7.428891] ? up_read (arch/x86/include/asm/preempt.h:104 kernel/locking/rwsem.c:1354 kernel/locking/rwsem.c:1616) [ 7.429514] ? bad_area_nosemaphore (arch/x86/mm/fault.c:867) [ 7.430367] ? do_user_addr_fault (arch/x86/mm/fault.c:1458) [ 7.431238] ? exc_page_fault (arch/x86/include/asm/paravirt.h:695 arch/x86/mm/fault.c:1495 arch/x86/mm/fault.c:1543) [ 7.431998] ? asm_exc_page_fault (arch/x86/include/asm/idtentry.h:570) [ 7.432802] ? __pfx__compound_head (include/linux/page-flags.h:245) [ 7.433640] ? do_pte_missing (mm/memory.c:4610 mm/memory.c:4682 mm/memory.c:3670) [ 7.434425] __handle_mm_fault (mm/memory.c:4947 mm/memory.c:5087) [ 7.435234] handle_mm_fault (mm/memory.c:5252) [ 7.435976] do_user_addr_fault (arch/x86/mm/fault.c:1393) [ 7.436786] exc_page_fault (arch/x86/include/asm/paravirt.h:695 arch/x86/mm/fault.c:1495 arch/x86/mm/fault.c:1543) [ 7.437517] asm_exc_page_fault (arch/x86/include/asm/idtentry.h:570) [ 7.438294] RIP: 0033:0x7f2ae1480ace [ 7.439035] Code: 8d a0 48 00 00 00 49 8b 44 24 08 48 0b 85 48 00 00 00 74 28 48 8d 3d f1 63 1d 00 e8f Code starting with the faulting instruction =========================================== 0: 8d a0 48 00 00 00 lea 0x48(%rax),%esp 6: 49 8b 44 24 08 mov 0x8(%r12),%rax b: 48 0b 85 48 00 00 00 or 0x48(%rbp),%rax 12: 74 28 je 0x3c 14: 48 8d 3d f1 63 1d 00 lea 0x1d63f1(%rip),%rdi # 0x1d640c 1b: 8f .byte 0x8f [ 7.442519] RSP: 002b:00007ffdfa53bc70 EFLAGS: 00010246 [ 7.443524] RAX: 0000000000000000 RBX: 00007f2ae19a7028 RCX: fffffffffffff000 [ 7.444857] RDX: 00007f2ae0f412e0 RSI: a3d70a3d70a3d70b RDI: 00007f2ae1656eb0 [ 7.446195] RBP: 00007f2ae0f40828 R08: 0000000000000001 R09: 00007f2ae19a7000 [ 7.447572] R10: 000055f8d50a1010 R11: 0000000000000246 R12: 00007f2ae0f40870 [ 7.448939] R13: 000055f8d50a7110 R14: 000055f8d50a2fd0 R15: 0000000000000001 [ 7.450277] [ 7.450725] Modules linked in: ip_tables x_tables autofs4 raid10 raid456 libcrc32c async_raid6_recov 4 [ 7.454653] Dumping ftrace buffer: [ 7.455321] (ftrace buffer empty) [ 7.456014] CR2: 0000000000000008 [ 7.456686] ---[ end trace 0000000000000000 ]--- [ 7.457576] RIP: 0010:_compound_head (include/linux/page-flags.h:245) [ 7.458440] Code: e8 35 b5 cd ff 5d c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90f Code starting with the faulting instruction =========================================== 0: e8 35 b5 cd ff callq 0xffffffffffcdb53a 5: 5d pop %rbp 6: c3 retq 7: cc int3 8: cc int3 9: cc int3 a: cc int3 b: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1) 12: 00 00 00 00 16: 0f 1f 40 00 nopl 0x0(%rax) 1a: 90 nop 1b: 0f .byte 0xf [ 7.461986] RSP: 0000:ffffb86140cd3d58 EFLAGS: 00010202 [ 7.463014] RAX: ffff96d3c19c4d38 RBX: ffffffffa103f080 RCX: 00000001019c4067 [ 7.464374] RDX: 0000000000000000 RSI: ffff96d2c0000d38 RDI: 0000000000000000 [ 7.465731] RBP: ffffb86140cd3d90 R08: ffff96d3c19c4d38 R09: 0000000000000067 [ 7.467114] R10: 0000000000000000 R11: 00007f2ae19d5fff R12: ffffb86140cd3dd0 [ 7.468469] R13: 0000000000000001 R14: ffff96d3cb7aa450 R15: 0000000000000860 [ 7.469824] FS: 00007f2ae0f40980(0000) GS:ffff96f1fd640000(0000) knlGS:0000000000000000 [ 7.471383] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 7.472482] CR2: 0000000000000008 CR3: 0000000104830000 CR4: 00000000000006e0 [ 7.473835] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 7.475216] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Thanks, SJ