* [PATCH] mm: fix kernel crash in khugepaged thread @ 2015-10-23 9:38 yalin wang 2015-10-23 10:11 ` Kirill A. Shutemov 0 siblings, 1 reply; 4+ messages in thread From: yalin wang @ 2015-10-23 9:38 UTC (permalink / raw) To: akpm, kirill.shutemov, vbabka, jmarchan, mgorman, ebru.akagunduz, willy, linux-mm, linux-kernel Cc: yalin wang This crash is caused by NULL pointer deference: [ 182.639154 ] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 182.639491 ] pgd = ffffffc00077a000 [ 182.639761 ] [00000000] *pgd=00000000b9422003, *pud=00000000b9422003, *pmd=00000000b9423003, *pte=0060000008000707 [ 182.640749 ] Internal error: Oops: 94000006 [#1] SMP [ 182.641197 ] Modules linked in: [ 182.641580 ] CPU: 1 PID: 26 Comm: khugepaged Tainted: G W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 [ 182.642077 ] Hardware name: linux,dummy-virt (DT) [ 182.642227 ] task: ffffffc07957c080 ti: ffffffc079638000 task.ti: ffffffc079638000 [ 182.642598 ] PC is at khugepaged+0x378/0x1af8 [ 182.642826 ] LR is at khugepaged+0x418/0x1af8 [ 182.643047 ] pc : [<ffffffc0001980ac>] lr : [<ffffffc00019814c>] pstate: 60000145 [ 182.643490 ] sp : ffffffc07963bca0 [ 182.643650 ] x29: ffffffc07963bca0 x28: ffffffc00075c000 [ 182.644024 ] x27: ffffffc00f275040 x26: ffffffc0006c7000 [ 182.644334 ] x25: 00e8000048800f51 x24: 0000000006400000 [ 182.644687 ] x23: 0000000000000002 x22: 0000000000000000 [ 182.644972 ] x21: 0000000000000000 x20: 0000000000000000 [ 182.645446 ] x19: 0000000000000000 x18: 0000007ff86d0990 [ 182.645931 ] x17: 00000000007ef9c8 x16: ffffffc000098390 [ 182.646236 ] x15: ffffffffffffffff x14: 00000000ffffffff [ 182.646649 ] x13: 000000000000016a x12: 0000000000000000 [ 182.647046 ] x11: ffffffc07f025020 x10: 0000000000000000 [ 182.647395 ] x9 : 0000000000000048 x8 : ffffffc000721e28 [ 182.647872 ] x7 : 0000000000000000 x6 : ffffffc07f02d000 [ 182.648261 ] x5 : fffffffffffffe00 x4 : ffffffc00f275040 [ 182.648611 ] x3 : 0000000000000000 x2 : ffffffc00f2ad000 [ 182.648908 ] x1 : 0000000000000000 x0 : ffffffc000727000 [ 182.649147 ] [ 182.649252 ] Process khugepaged (pid: 26, stack limit = 0xffffffc079638020) [ 182.649724 ] Stack: (0xffffffc07963bca0 to 0xffffffc07963c000) [ 182.650141 ] bca0: ffffffc07963be30 ffffffc0000b5044 ffffffc07961fb80 ffffffc00072e630 [ 182.650587 ] bcc0: ffffffc0005d5090 0000000000000000 ffffffc000197d34 0000000000000000 [ 182.651009 ] bce0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.651446 ] bd00: ffffffc07963bd90 ffffffc07f1cbf80 000000004f3be003 ffffffc00f2750a4 [ 182.651956 ] bd20: ffffffc00f3bf000 ffffffc000000001 0000000000000001 ffffffc07f085740 [ 182.652520 ] bd40: ffffffc00f2ad188 ffffffc000000000 0000000006200000 ffffffc00f275040 [ 182.652972 ] bd60: ffffffc0006b1a90 ffffffc079638000 ffffffc07963be20 ffffffc00f0144d0 [ 182.653357 ] bd80: ffffffc000000000 0000000006400000 ffffffc00f0144d0 00000a0800000001 [ 182.653793 ] bda0: 0000100000000001 ffffffc000000001 ffffffc07f025000 ffffffc00f2750a8 [ 182.654226 ] bdc0: 00000001000005f8 ffffffc00075a000 0000000006a00000 ffffffc000727000 [ 182.654522 ] bde0: ffffffc0006e8478 ffffffc000000000 0000000100000000 ffffffc078fb9000 [ 182.654869 ] be00: ffffffc07963be30 ffffffc000000000 ffffffc07957c080 ffffffc0000cfc4c [ 182.655225 ] be20: ffffffc07963be20 ffffffc07963be20 0000000000000000 ffffffc000085c50 [ 182.655588 ] be40: ffffffc0000b4f64 ffffffc07961fb80 0000000000000000 0000000000000000 [ 182.656138 ] be60: 0000000000000000 ffffffc0000bee2c ffffffc0000b4f64 0000000000000000 [ 182.656609 ] be80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.657145 ] bea0: ffffffc07963bea0 ffffffc07963bea0 0000000000000000 ffffffc000000000 [ 182.657475 ] bec0: ffffffc07963bec0 ffffffc07963bec0 0000000000000000 0000000000000000 [ 182.657922 ] bee0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.658558 ] bf00: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.658972 ] bf20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.659291 ] bf40: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.659722 ] bf60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.660122 ] bf80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.660654 ] bfa0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.661064 ] bfc0: 0000000000000000 0000000000000000 0000000000000000 0000000000000005 [ 182.661466 ] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 182.661848 ] Call trace: [ 182.662050 ] [<ffffffc0001980ac>] khugepaged+0x378/0x1af8 [ 182.662294 ] [<ffffffc0000b5040>] kthread+0xdc/0xf4 [ 182.662605 ] [<ffffffc000085c4c>] ret_from_fork+0xc/0x40 [ 182.663046 ] Code: 35001700 f0002c60 aa0703e3 f9009fa0 (f94000e0) [ 182.663901 ] ---[ end trace 637503d8e28ae69e ]--- [ 182.664160 ] Kernel panic - not syncing: Fatal exception [ 182.664571 ] CPU2: stopping [ 182.664794 ] CPU: 2 PID: 0 Comm: swapper/2 Tainted: G D W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 [ 182.665248 ] Hardware name: linux,dummy-virt (DT) Signed-off-by: yalin wang <yalin.wang2010@gmail.com> --- mm/huge_memory.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4b3420a..a5f4d9c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2606,8 +2606,9 @@ out_unmap: collapse_huge_page(mm, address, hpage, vma, node); } out: - trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, - none_or_zero, result, unmapped); + if (page) + trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, + referenced, none_or_zero, result, unmapped); return ret; } -- 1.9.1 -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix kernel crash in khugepaged thread 2015-10-23 9:38 [PATCH] mm: fix kernel crash in khugepaged thread yalin wang @ 2015-10-23 10:11 ` Kirill A. Shutemov 2015-10-23 16:00 ` yalin wang 0 siblings, 1 reply; 4+ messages in thread From: Kirill A. Shutemov @ 2015-10-23 10:11 UTC (permalink / raw) To: yalin wang Cc: akpm, kirill.shutemov, vbabka, jmarchan, mgorman, ebru.akagunduz, willy, linux-mm, linux-kernel On Fri, Oct 23, 2015 at 05:38:49PM +0800, yalin wang wrote: > This crash is caused by NULL pointer deference: > [ 182.639154 ] Unable to handle kernel NULL pointer dereference at virtual address 00000000 > [ 182.639491 ] pgd = ffffffc00077a000 > [ 182.639761 ] [00000000] *pgd=00000000b9422003, *pud=00000000b9422003, *pmd=00000000b9423003, *pte=0060000008000707 > [ 182.640749 ] Internal error: Oops: 94000006 [#1] SMP > [ 182.641197 ] Modules linked in: > [ 182.641580 ] CPU: 1 PID: 26 Comm: khugepaged Tainted: G W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 > [ 182.642077 ] Hardware name: linux,dummy-virt (DT) > [ 182.642227 ] task: ffffffc07957c080 ti: ffffffc079638000 task.ti: ffffffc079638000 > [ 182.642598 ] PC is at khugepaged+0x378/0x1af8 > [ 182.642826 ] LR is at khugepaged+0x418/0x1af8 > [ 182.643047 ] pc : [<ffffffc0001980ac>] lr : [<ffffffc00019814c>] pstate: 60000145 > [ 182.643490 ] sp : ffffffc07963bca0 > [ 182.643650 ] x29: ffffffc07963bca0 x28: ffffffc00075c000 > [ 182.644024 ] x27: ffffffc00f275040 x26: ffffffc0006c7000 > [ 182.644334 ] x25: 00e8000048800f51 x24: 0000000006400000 > [ 182.644687 ] x23: 0000000000000002 x22: 0000000000000000 > [ 182.644972 ] x21: 0000000000000000 x20: 0000000000000000 > [ 182.645446 ] x19: 0000000000000000 x18: 0000007ff86d0990 > [ 182.645931 ] x17: 00000000007ef9c8 x16: ffffffc000098390 > [ 182.646236 ] x15: ffffffffffffffff x14: 00000000ffffffff > [ 182.646649 ] x13: 000000000000016a x12: 0000000000000000 > [ 182.647046 ] x11: ffffffc07f025020 x10: 0000000000000000 > [ 182.647395 ] x9 : 0000000000000048 x8 : ffffffc000721e28 > [ 182.647872 ] x7 : 0000000000000000 x6 : ffffffc07f02d000 > [ 182.648261 ] x5 : fffffffffffffe00 x4 : ffffffc00f275040 > [ 182.648611 ] x3 : 0000000000000000 x2 : ffffffc00f2ad000 > [ 182.648908 ] x1 : 0000000000000000 x0 : ffffffc000727000 > [ 182.649147 ] > [ 182.649252 ] Process khugepaged (pid: 26, stack limit = 0xffffffc079638020) > [ 182.649724 ] Stack: (0xffffffc07963bca0 to 0xffffffc07963c000) > [ 182.650141 ] bca0: ffffffc07963be30 ffffffc0000b5044 ffffffc07961fb80 ffffffc00072e630 > [ 182.650587 ] bcc0: ffffffc0005d5090 0000000000000000 ffffffc000197d34 0000000000000000 > [ 182.651009 ] bce0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.651446 ] bd00: ffffffc07963bd90 ffffffc07f1cbf80 000000004f3be003 ffffffc00f2750a4 > [ 182.651956 ] bd20: ffffffc00f3bf000 ffffffc000000001 0000000000000001 ffffffc07f085740 > [ 182.652520 ] bd40: ffffffc00f2ad188 ffffffc000000000 0000000006200000 ffffffc00f275040 > [ 182.652972 ] bd60: ffffffc0006b1a90 ffffffc079638000 ffffffc07963be20 ffffffc00f0144d0 > [ 182.653357 ] bd80: ffffffc000000000 0000000006400000 ffffffc00f0144d0 00000a0800000001 > [ 182.653793 ] bda0: 0000100000000001 ffffffc000000001 ffffffc07f025000 ffffffc00f2750a8 > [ 182.654226 ] bdc0: 00000001000005f8 ffffffc00075a000 0000000006a00000 ffffffc000727000 > [ 182.654522 ] bde0: ffffffc0006e8478 ffffffc000000000 0000000100000000 ffffffc078fb9000 > [ 182.654869 ] be00: ffffffc07963be30 ffffffc000000000 ffffffc07957c080 ffffffc0000cfc4c > [ 182.655225 ] be20: ffffffc07963be20 ffffffc07963be20 0000000000000000 ffffffc000085c50 > [ 182.655588 ] be40: ffffffc0000b4f64 ffffffc07961fb80 0000000000000000 0000000000000000 > [ 182.656138 ] be60: 0000000000000000 ffffffc0000bee2c ffffffc0000b4f64 0000000000000000 > [ 182.656609 ] be80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.657145 ] bea0: ffffffc07963bea0 ffffffc07963bea0 0000000000000000 ffffffc000000000 > [ 182.657475 ] bec0: ffffffc07963bec0 ffffffc07963bec0 0000000000000000 0000000000000000 > [ 182.657922 ] bee0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.658558 ] bf00: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.658972 ] bf20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.659291 ] bf40: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.659722 ] bf60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.660122 ] bf80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.660654 ] bfa0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.661064 ] bfc0: 0000000000000000 0000000000000000 0000000000000000 0000000000000005 > [ 182.661466 ] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > [ 182.661848 ] Call trace: > [ 182.662050 ] [<ffffffc0001980ac>] khugepaged+0x378/0x1af8 > [ 182.662294 ] [<ffffffc0000b5040>] kthread+0xdc/0xf4 > [ 182.662605 ] [<ffffffc000085c4c>] ret_from_fork+0xc/0x40 > [ 182.663046 ] Code: 35001700 f0002c60 aa0703e3 f9009fa0 (f94000e0) > [ 182.663901 ] ---[ end trace 637503d8e28ae69e ]--- > [ 182.664160 ] Kernel panic - not syncing: Fatal exception > [ 182.664571 ] CPU2: stopping > [ 182.664794 ] CPU: 2 PID: 0 Comm: swapper/2 Tainted: G D W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 > [ 182.665248 ] Hardware name: linux,dummy-virt (DT) > > Signed-off-by: yalin wang <yalin.wang2010@gmail.com> > --- > mm/huge_memory.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 4b3420a..a5f4d9c 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2606,8 +2606,9 @@ out_unmap: > collapse_huge_page(mm, address, hpage, vma, node); > } > out: > - trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, > - none_or_zero, result, unmapped); > + if (page) > + trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, > + referenced, none_or_zero, result, unmapped); > return ret; > } What about this instead? diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4b3420ade697..392ebba27fe2 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2503,10 +2503,8 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, VM_BUG_ON(address & ~HPAGE_PMD_MASK); pmd = mm_find_pmd(mm, address); - if (!pmd) { - result = SCAN_PMD_NULL; - goto out; - } + if (!pmd) + return 0; memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load)); pte = pte_offset_map_lock(mm, pmd, address, &ptl); @@ -2605,7 +2603,6 @@ out_unmap: /* collapse_huge_page will return with the mmap_sem released */ collapse_huge_page(mm, address, hpage, vma, node); } -out: trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, none_or_zero, result, unmapped); return ret; -- Kirill A. Shutemov -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix kernel crash in khugepaged thread 2015-10-23 10:11 ` Kirill A. Shutemov @ 2015-10-23 16:00 ` yalin wang 2015-10-23 19:28 ` Kirill A. Shutemov 0 siblings, 1 reply; 4+ messages in thread From: yalin wang @ 2015-10-23 16:00 UTC (permalink / raw) To: Kirill A. Shutemov Cc: Andrew Morton, Kirill A. Shutemov, Vlastimil Babka, jmarchan, mgorman, Ebru Akagunduz, willy, linux-mm, linux-kernel > On Oct 23, 2015, at 18:11, Kirill A. Shutemov <kirill@shutemov.name> wrote: > > On Fri, Oct 23, 2015 at 05:38:49PM +0800, yalin wang wrote: >> This crash is caused by NULL pointer deference: >> [ 182.639154 ] Unable to handle kernel NULL pointer dereference at virtual address 00000000 >> [ 182.639491 ] pgd = ffffffc00077a000 >> [ 182.639761 ] [00000000] *pgd=00000000b9422003, *pud=00000000b9422003, *pmd=00000000b9423003, *pte=0060000008000707 >> [ 182.640749 ] Internal error: Oops: 94000006 [#1] SMP >> [ 182.641197 ] Modules linked in: >> [ 182.641580 ] CPU: 1 PID: 26 Comm: khugepaged Tainted: G W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 >> [ 182.642077 ] Hardware name: linux,dummy-virt (DT) >> [ 182.642227 ] task: ffffffc07957c080 ti: ffffffc079638000 task.ti: ffffffc079638000 >> [ 182.642598 ] PC is at khugepaged+0x378/0x1af8 >> [ 182.642826 ] LR is at khugepaged+0x418/0x1af8 >> [ 182.643047 ] pc : [<ffffffc0001980ac>] lr : [<ffffffc00019814c>] pstate: 60000145 >> [ 182.643490 ] sp : ffffffc07963bca0 >> [ 182.643650 ] x29: ffffffc07963bca0 x28: ffffffc00075c000 >> [ 182.644024 ] x27: ffffffc00f275040 x26: ffffffc0006c7000 >> [ 182.644334 ] x25: 00e8000048800f51 x24: 0000000006400000 >> [ 182.644687 ] x23: 0000000000000002 x22: 0000000000000000 >> [ 182.644972 ] x21: 0000000000000000 x20: 0000000000000000 >> [ 182.645446 ] x19: 0000000000000000 x18: 0000007ff86d0990 >> [ 182.645931 ] x17: 00000000007ef9c8 x16: ffffffc000098390 >> [ 182.646236 ] x15: ffffffffffffffff x14: 00000000ffffffff >> [ 182.646649 ] x13: 000000000000016a x12: 0000000000000000 >> [ 182.647046 ] x11: ffffffc07f025020 x10: 0000000000000000 >> [ 182.647395 ] x9 : 0000000000000048 x8 : ffffffc000721e28 >> [ 182.647872 ] x7 : 0000000000000000 x6 : ffffffc07f02d000 >> [ 182.648261 ] x5 : fffffffffffffe00 x4 : ffffffc00f275040 >> [ 182.648611 ] x3 : 0000000000000000 x2 : ffffffc00f2ad000 >> [ 182.648908 ] x1 : 0000000000000000 x0 : ffffffc000727000 >> [ 182.649147 ] >> [ 182.649252 ] Process khugepaged (pid: 26, stack limit = 0xffffffc079638020) >> [ 182.649724 ] Stack: (0xffffffc07963bca0 to 0xffffffc07963c000) >> [ 182.650141 ] bca0: ffffffc07963be30 ffffffc0000b5044 ffffffc07961fb80 ffffffc00072e630 >> [ 182.650587 ] bcc0: ffffffc0005d5090 0000000000000000 ffffffc000197d34 0000000000000000 >> [ 182.651009 ] bce0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.651446 ] bd00: ffffffc07963bd90 ffffffc07f1cbf80 000000004f3be003 ffffffc00f2750a4 >> [ 182.651956 ] bd20: ffffffc00f3bf000 ffffffc000000001 0000000000000001 ffffffc07f085740 >> [ 182.652520 ] bd40: ffffffc00f2ad188 ffffffc000000000 0000000006200000 ffffffc00f275040 >> [ 182.652972 ] bd60: ffffffc0006b1a90 ffffffc079638000 ffffffc07963be20 ffffffc00f0144d0 >> [ 182.653357 ] bd80: ffffffc000000000 0000000006400000 ffffffc00f0144d0 00000a0800000001 >> [ 182.653793 ] bda0: 0000100000000001 ffffffc000000001 ffffffc07f025000 ffffffc00f2750a8 >> [ 182.654226 ] bdc0: 00000001000005f8 ffffffc00075a000 0000000006a00000 ffffffc000727000 >> [ 182.654522 ] bde0: ffffffc0006e8478 ffffffc000000000 0000000100000000 ffffffc078fb9000 >> [ 182.654869 ] be00: ffffffc07963be30 ffffffc000000000 ffffffc07957c080 ffffffc0000cfc4c >> [ 182.655225 ] be20: ffffffc07963be20 ffffffc07963be20 0000000000000000 ffffffc000085c50 >> [ 182.655588 ] be40: ffffffc0000b4f64 ffffffc07961fb80 0000000000000000 0000000000000000 >> [ 182.656138 ] be60: 0000000000000000 ffffffc0000bee2c ffffffc0000b4f64 0000000000000000 >> [ 182.656609 ] be80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.657145 ] bea0: ffffffc07963bea0 ffffffc07963bea0 0000000000000000 ffffffc000000000 >> [ 182.657475 ] bec0: ffffffc07963bec0 ffffffc07963bec0 0000000000000000 0000000000000000 >> [ 182.657922 ] bee0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.658558 ] bf00: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.658972 ] bf20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.659291 ] bf40: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.659722 ] bf60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.660122 ] bf80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.660654 ] bfa0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.661064 ] bfc0: 0000000000000000 0000000000000000 0000000000000000 0000000000000005 >> [ 182.661466 ] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 182.661848 ] Call trace: >> [ 182.662050 ] [<ffffffc0001980ac>] khugepaged+0x378/0x1af8 >> [ 182.662294 ] [<ffffffc0000b5040>] kthread+0xdc/0xf4 >> [ 182.662605 ] [<ffffffc000085c4c>] ret_from_fork+0xc/0x40 >> [ 182.663046 ] Code: 35001700 f0002c60 aa0703e3 f9009fa0 (f94000e0) >> [ 182.663901 ] ---[ end trace 637503d8e28ae69e ]--- >> [ 182.664160 ] Kernel panic - not syncing: Fatal exception >> [ 182.664571 ] CPU2: stopping >> [ 182.664794 ] CPU: 2 PID: 0 Comm: swapper/2 Tainted: G D W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 >> [ 182.665248 ] Hardware name: linux,dummy-virt (DT) >> >> Signed-off-by: yalin wang <yalin.wang2010@gmail.com> >> --- >> mm/huge_memory.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index 4b3420a..a5f4d9c 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -2606,8 +2606,9 @@ out_unmap: >> collapse_huge_page(mm, address, hpage, vma, node); >> } >> out: >> - trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, >> - none_or_zero, result, unmapped); >> + if (page) >> + trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, >> + referenced, none_or_zero, result, unmapped); >> return ret; >> } > > What about this instead? > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 4b3420ade697..392ebba27fe2 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2503,10 +2503,8 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > > pmd = mm_find_pmd(mm, address); > - if (!pmd) { > - result = SCAN_PMD_NULL; > - goto out; > - } > + if (!pmd) > + return 0; it is not safe to add return here, there is lots of place which goto out_unmap below mm_find_pmd() , like page = vm_normal_page(vma, _address, pteval); if page == NULL here , will also result in NULL pointer deference crash . Thanks -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix kernel crash in khugepaged thread 2015-10-23 16:00 ` yalin wang @ 2015-10-23 19:28 ` Kirill A. Shutemov 0 siblings, 0 replies; 4+ messages in thread From: Kirill A. Shutemov @ 2015-10-23 19:28 UTC (permalink / raw) To: yalin wang Cc: Andrew Morton, Kirill A. Shutemov, Vlastimil Babka, jmarchan, mgorman, Ebru Akagunduz, willy, linux-mm, linux-kernel On Sat, Oct 24, 2015 at 12:00:14AM +0800, yalin wang wrote: > > > On Oct 23, 2015, at 18:11, Kirill A. Shutemov <kirill@shutemov.name> wrote: > > > > On Fri, Oct 23, 2015 at 05:38:49PM +0800, yalin wang wrote: > >> This crash is caused by NULL pointer deference: > >> [ 182.639154 ] Unable to handle kernel NULL pointer dereference at virtual address 00000000 > >> [ 182.639491 ] pgd = ffffffc00077a000 > >> [ 182.639761 ] [00000000] *pgd=00000000b9422003, *pud=00000000b9422003, *pmd=00000000b9423003, *pte=0060000008000707 > >> [ 182.640749 ] Internal error: Oops: 94000006 [#1] SMP > >> [ 182.641197 ] Modules linked in: > >> [ 182.641580 ] CPU: 1 PID: 26 Comm: khugepaged Tainted: G W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 > >> [ 182.642077 ] Hardware name: linux,dummy-virt (DT) > >> [ 182.642227 ] task: ffffffc07957c080 ti: ffffffc079638000 task.ti: ffffffc079638000 > >> [ 182.642598 ] PC is at khugepaged+0x378/0x1af8 > >> [ 182.642826 ] LR is at khugepaged+0x418/0x1af8 > >> [ 182.643047 ] pc : [<ffffffc0001980ac>] lr : [<ffffffc00019814c>] pstate: 60000145 > >> [ 182.643490 ] sp : ffffffc07963bca0 > >> [ 182.643650 ] x29: ffffffc07963bca0 x28: ffffffc00075c000 > >> [ 182.644024 ] x27: ffffffc00f275040 x26: ffffffc0006c7000 > >> [ 182.644334 ] x25: 00e8000048800f51 x24: 0000000006400000 > >> [ 182.644687 ] x23: 0000000000000002 x22: 0000000000000000 > >> [ 182.644972 ] x21: 0000000000000000 x20: 0000000000000000 > >> [ 182.645446 ] x19: 0000000000000000 x18: 0000007ff86d0990 > >> [ 182.645931 ] x17: 00000000007ef9c8 x16: ffffffc000098390 > >> [ 182.646236 ] x15: ffffffffffffffff x14: 00000000ffffffff > >> [ 182.646649 ] x13: 000000000000016a x12: 0000000000000000 > >> [ 182.647046 ] x11: ffffffc07f025020 x10: 0000000000000000 > >> [ 182.647395 ] x9 : 0000000000000048 x8 : ffffffc000721e28 > >> [ 182.647872 ] x7 : 0000000000000000 x6 : ffffffc07f02d000 > >> [ 182.648261 ] x5 : fffffffffffffe00 x4 : ffffffc00f275040 > >> [ 182.648611 ] x3 : 0000000000000000 x2 : ffffffc00f2ad000 > >> [ 182.648908 ] x1 : 0000000000000000 x0 : ffffffc000727000 > >> [ 182.649147 ] > >> [ 182.649252 ] Process khugepaged (pid: 26, stack limit = 0xffffffc079638020) > >> [ 182.649724 ] Stack: (0xffffffc07963bca0 to 0xffffffc07963c000) > >> [ 182.650141 ] bca0: ffffffc07963be30 ffffffc0000b5044 ffffffc07961fb80 ffffffc00072e630 > >> [ 182.650587 ] bcc0: ffffffc0005d5090 0000000000000000 ffffffc000197d34 0000000000000000 > >> [ 182.651009 ] bce0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.651446 ] bd00: ffffffc07963bd90 ffffffc07f1cbf80 000000004f3be003 ffffffc00f2750a4 > >> [ 182.651956 ] bd20: ffffffc00f3bf000 ffffffc000000001 0000000000000001 ffffffc07f085740 > >> [ 182.652520 ] bd40: ffffffc00f2ad188 ffffffc000000000 0000000006200000 ffffffc00f275040 > >> [ 182.652972 ] bd60: ffffffc0006b1a90 ffffffc079638000 ffffffc07963be20 ffffffc00f0144d0 > >> [ 182.653357 ] bd80: ffffffc000000000 0000000006400000 ffffffc00f0144d0 00000a0800000001 > >> [ 182.653793 ] bda0: 0000100000000001 ffffffc000000001 ffffffc07f025000 ffffffc00f2750a8 > >> [ 182.654226 ] bdc0: 00000001000005f8 ffffffc00075a000 0000000006a00000 ffffffc000727000 > >> [ 182.654522 ] bde0: ffffffc0006e8478 ffffffc000000000 0000000100000000 ffffffc078fb9000 > >> [ 182.654869 ] be00: ffffffc07963be30 ffffffc000000000 ffffffc07957c080 ffffffc0000cfc4c > >> [ 182.655225 ] be20: ffffffc07963be20 ffffffc07963be20 0000000000000000 ffffffc000085c50 > >> [ 182.655588 ] be40: ffffffc0000b4f64 ffffffc07961fb80 0000000000000000 0000000000000000 > >> [ 182.656138 ] be60: 0000000000000000 ffffffc0000bee2c ffffffc0000b4f64 0000000000000000 > >> [ 182.656609 ] be80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.657145 ] bea0: ffffffc07963bea0 ffffffc07963bea0 0000000000000000 ffffffc000000000 > >> [ 182.657475 ] bec0: ffffffc07963bec0 ffffffc07963bec0 0000000000000000 0000000000000000 > >> [ 182.657922 ] bee0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.658558 ] bf00: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.658972 ] bf20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.659291 ] bf40: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.659722 ] bf60: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.660122 ] bf80: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.660654 ] bfa0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.661064 ] bfc0: 0000000000000000 0000000000000000 0000000000000000 0000000000000005 > >> [ 182.661466 ] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > >> [ 182.661848 ] Call trace: > >> [ 182.662050 ] [<ffffffc0001980ac>] khugepaged+0x378/0x1af8 > >> [ 182.662294 ] [<ffffffc0000b5040>] kthread+0xdc/0xf4 > >> [ 182.662605 ] [<ffffffc000085c4c>] ret_from_fork+0xc/0x40 > >> [ 182.663046 ] Code: 35001700 f0002c60 aa0703e3 f9009fa0 (f94000e0) > >> [ 182.663901 ] ---[ end trace 637503d8e28ae69e ]--- > >> [ 182.664160 ] Kernel panic - not syncing: Fatal exception > >> [ 182.664571 ] CPU2: stopping > >> [ 182.664794 ] CPU: 2 PID: 0 Comm: swapper/2 Tainted: G D W 4.3.0-rc6-next-20151022ajb-00001-g32f3386-dirty #3 > >> [ 182.665248 ] Hardware name: linux,dummy-virt (DT) > >> > >> Signed-off-by: yalin wang <yalin.wang2010@gmail.com> > >> --- > >> mm/huge_memory.c | 5 +++-- > >> 1 file changed, 3 insertions(+), 2 deletions(-) > >> > >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c > >> index 4b3420a..a5f4d9c 100644 > >> --- a/mm/huge_memory.c > >> +++ b/mm/huge_memory.c > >> @@ -2606,8 +2606,9 @@ out_unmap: > >> collapse_huge_page(mm, address, hpage, vma, node); > >> } > >> out: > >> - trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced, > >> - none_or_zero, result, unmapped); > >> + if (page) > >> + trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, > >> + referenced, none_or_zero, result, unmapped); > >> return ret; > >> } > > > > What about this instead? > > > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > > index 4b3420ade697..392ebba27fe2 100644 > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -2503,10 +2503,8 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, > > VM_BUG_ON(address & ~HPAGE_PMD_MASK); > > > > pmd = mm_find_pmd(mm, address); > > - if (!pmd) { > > - result = SCAN_PMD_NULL; > > - goto out; > > - } > > + if (!pmd) > > + return 0; > > it is not safe to add return here, > there is lots of place which goto out_unmap below mm_find_pmd() , > like page = vm_normal_page(vma, _address, pteval); > if page == NULL here , will also result in NULL pointer deference crash . Fair enough. But there is no point to set 'result' for these cases. -- Kirill A. Shutemov -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-10-23 19:28 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2015-10-23 9:38 [PATCH] mm: fix kernel crash in khugepaged thread yalin wang 2015-10-23 10:11 ` Kirill A. Shutemov 2015-10-23 16:00 ` yalin wang 2015-10-23 19:28 ` Kirill A. Shutemov
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