Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752125AbaB1JCZ (ORCPT ); Fri, 28 Feb 2014 04:02:25 -0500 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:46787 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752057AbaB1JCV (ORCPT ); Fri, 28 Feb 2014 04:02:21 -0500 From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, akpm@linux-foundation.org, Peter Zijlstra Cc: linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Liu Ping Fan , "Aneesh Kumar K.V" Subject: [PATCH V3] mm: numa: bugfix for LAST_CPUPID_NOT_IN_PAGE_FLAGS Date: Fri, 28 Feb 2014 14:32:02 +0530 Message-Id: <1393578122-6500-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.3.2 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14022809-9264-0000-0000-0000058D1226 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Liu Ping Fan When doing some numa tests on powerpc, I triggered an oops bug. I find it is caused by using page->_last_cpupid. It should be initialized as "-1 & LAST_CPUPID_MASK", but not "-1". Otherwise, in task_numa_fault(), we will miss the checking (last_cpupid == (-1 & LAST_CPUPID_MASK)). And finally cause an oops bug in task_numa_group(), since the online cpu is less than possible cpu. This happen with CONFIG_SPARSE_VMEMMAP disabled Call trace: [ 55.978091] SMP NR_CPUS=64 NUMA PowerNV [ 55.978118] Modules linked in: [ 55.978145] CPU: 24 PID: 804 Comm: systemd-udevd Not tainted3.13.0-rc1+ #32 [ 55.978183] task: c000001e2746aa80 ti: c000001e32c50000 task.ti:c000001e32c50000 [ 55.978219] NIP: c0000000000f5ad0 LR: c0000000000f5ac8 CTR:c000000000913cf0 [ 55.978256] REGS: c000001e32c53510 TRAP: 0300 Not tainted(3.13.0-rc1+) [ 55.978286] MSR: 9000000000009032 CR:28024424 XER: 20000000 [ 55.978380] CFAR: c000000000009324 DAR: 7265717569726857 DSISR:40000000 SOFTE: 1 GPR00: c0000000000f5ac8 c000001e32c53790 c000000001f343380000000000000021 GPR04: 0000000000000000 0000000000000031 c000000001f743380000ffffffffffff GPR08: 0000000000000001 7265717569726573 00000000000000000000000000000000 GPR12: 0000000028024422 c00000000ffdd800 00000000296b2e640000000000000020 GPR16: 0000000000000002 0000000000000003 c000001e2f8e4658c000001e25c1c1d8 GPR20: c000001e2f8e4000 c000000001f7a858 00000000000006580000000040000392 GPR24: 00000000000000a8 c000001e33c1a400 00000000000001d8c000001e25c1c000 GPR28: c000001e33c37ff0 0007837840000392 000000000000003fc000001e32c53790 [ 55.978903] NIP [c0000000000f5ad0] .task_numa_fault+0x1470/0x2370 [ 55.978934] LR [c0000000000f5ac8] .task_numa_fault+0x1468/0x2370 [ 55.978964] Call Trace: [ 55.978978] [c000001e32c53790] [c0000000000f5ac8].task_numa_fault+0x1468/0x2370 (unreliable) [ 55.979036] [c000001e32c539e0] [c00000000020a820].do_numa_page+0x480/0x4a0 [ 55.979072] [c000001e32c53b10] [c00000000020bfec].handle_mm_fault+0x4ec/0xc90 [ 55.979123] [c000001e32c53c00] [c000000000e88c98].do_page_fault+0x3a8/0x890 [ 55.979161] [c000001e32c53e30] [c000000000009568]handle_page_fault+0x10/0x30 [ 55.979197] Instruction dump: [ 55.979216] 3c82fefb 3884b138 48d9cff1 60000000 48000574 3c62fefb3863af78 3c82fefb [ 55.979277] 3884b138 48d9cfd5 60000000 e93f0100 <812902e4> 7d2907b45529063e 7d2a07b4 [ 55.979354] ---[ end trace 15f2510da5ae07cf ]--- Signed-off-by: Liu Ping Fan Signed-off-by: Aneesh Kumar K.V --- Changes from V2: * Also updated cpupid_xchg_last to use LAST_CPUPID_MASK. We use the that function with value -1 * Update Author information after taking to Liu include/linux/mm.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index f28f46eade6a..86245839c9fa 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -757,7 +757,7 @@ static inline bool __cpupid_match_pid(pid_t task_pid, int cpupid) #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS static inline int page_cpupid_xchg_last(struct page *page, int cpupid) { - return xchg(&page->_last_cpupid, cpupid); + return xchg(&page->_last_cpupid, cpupid & LAST_CPUPID_MASK); } static inline int page_cpupid_last(struct page *page) @@ -766,7 +766,7 @@ static inline int page_cpupid_last(struct page *page) } static inline void page_cpupid_reset_last(struct page *page) { - page->_last_cpupid = -1; + page->_last_cpupid = -1 & LAST_CPUPID_MASK; } #else static inline int page_cpupid_last(struct page *page) -- 1.8.3.2 -- 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/