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Message-Id: <1445855960-28677-1-git-send-email-yalin.wang2010@gmail.com>
Date: Mon, 26 Oct 2015 18:39:20 +0800
From: yalin wang <yalin.wang2010@...il.com>
To: akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com,
vbabka@...e.cz, jmarchan@...hat.com, mgorman@...hsingularity.net,
ebru.akagunduz@...il.com, willy@...ux.intel.com,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: yalin wang <yalin.wang2010@...il.com>
Subject: [PATCH V2] mm: fix kernel crash in khugepaged thread
This crash is caused by NULL pointer deference, in page_to_pfn() marco,
when page == NULL :
[ 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@...il.com>
---
mm/huge_memory.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 4b3420a..8a3482f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2492,7 +2492,7 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
struct page **hpage)
{
pmd_t *pmd;
- pte_t *pte, *_pte;
+ pte_t *pte, *_pte, uninitialized_var(pteval);
int ret = 0, none_or_zero = 0, result = 0;
struct page *page = NULL;
unsigned long _address;
@@ -2503,16 +2503,14 @@ 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 ret;
memset(khugepaged_node_load, 0, sizeof(khugepaged_node_load));
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
for (_address = address, _pte = pte; _pte < pte+HPAGE_PMD_NR;
_pte++, _address += PAGE_SIZE) {
- pte_t pteval = *_pte;
+ pteval = *_pte;
if (is_swap_pte(pteval)) {
if (++unmapped <= khugepaged_max_ptes_swap) {
continue;
@@ -2605,9 +2603,9 @@ 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);
+ trace_mm_khugepaged_scan_pmd(mm, pte_present(pteval) ?
+ pte_pfn(pteval) : -1, writable, referenced,
+ none_or_zero, result, unmapped);
return ret;
}
--
1.9.1
--
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