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Date: Tue, 19 Jan 2016 11:02:12 +0300
From: Cyrill Gorcunov <gorcunov@...il.com>
To: kernel test robot <ying.huang@...ux.intel.com>
Cc: Ebru Akagunduz <ebru.akagunduz@...il.com>, lkp@...org,
LKML <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Dan Carpenter <dan.carpenter@...cle.com>,
Michal Hocko <mhocko@...e.cz>,
Johannes Weiner <hannes@...xchg.org>,
Hugh Dickins <hughd@...gle.com>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
Vlastimil Babka <vbabka@...e.cz>,
David Rientjes <rientjes@...gle.com>,
Mel Gorman <mgorman@...e.de>, Xie XiuQi <xiexiuqi@...wei.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Andrea Arcangeli <aarcange@...hat.com>,
Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
Rik van Riel <riel@...hat.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [lkp] [mm] 7d2eba0557: BUG: unable to handle kernel NULL pointer
dereference at (null)
On Tue, Jan 19, 2016 at 09:53:36AM +0800, kernel test robot wrote:
> FYI, we noticed the below changes on
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> commit 7d2eba0557c18f7522b98befed98799990dd4fdb ("mm: add tracepoint for scanning pages")
>
>
> +-----------------------------------------------------------+------------+------------+
> | | cb5490a5ee | 7d2eba0557 |
> +-----------------------------------------------------------+------------+------------+
> | boot_successes | 0 | 0 |
> | boot_failures | 12 | 12 |
> | BUG:kernel_test_oversize | 10 | |
> | Kernel_panic-not_syncing:Attempted_to_kill_init!exitcode= | 2 | 4 |
> | BUG:unable_to_handle_kernel | 0 | 8 |
> | Oops | 0 | 8 |
> | RIP:khugepaged_scan_pmd | 0 | 8 |
> | Kernel_panic-not_syncing:Fatal_exception | 0 | 8 |
> | backtrace:khugepaged | 0 | 8 |
> +-----------------------------------------------------------+------------+------------+
>
>
>
> [ 28.528131] systemd-journald[162]: Vacuuming...
> [ 28.543867] systemd-journald[162]: Vacuuming done, freed 0 bytes
> [ 28.548220] systemd-journald[162]: Flushing /dev/kmsg...
> [ 28.552721] BUG: unable to handle kernel NULL pointer dereference at (null)
> [ 28.553471] IP: [<ffffffffadeed16b>] khugepaged_scan_pmd+0x33b/0xaa0
> [ 28.553480] PGD 0
> [ 28.553484] Oops: 0000 [#1] PREEMPT SMP
> [ 28.553490] Modules linked in: autofs4
> [ 28.553497] CPU: 1 PID: 25 Comm: khugepaged Not tainted 4.4.0-05704-g7d2eba0 #1
> [ 28.553498] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
> [ 28.553501] task: ffff880035b75000 ti: ffff880035b78000 task.ti: ffff880035b78000
> [ 28.553503] RIP: 0010:[<ffffffffadeed16b>] [<ffffffffadeed16b>] khugepaged_scan_pmd+0x33b/0xaa0
> [ 28.553508] RSP: 0018:ffff880035b7bd20 EFLAGS: 00010246
> [ 28.553510] RAX: 0000000000000000 RBX: 0000000000000002 RCX: ffff880035b7bdf0
> [ 28.553512] RDX: ffff880000000000 RSI: 0000000000000000 RDI: 800000002f8000e7
> [ 28.553514] RBP: ffff880035b7bda0 R08: ffff8800155a6448 R09: 0000000000000000
> [ 28.553516] R10: 0000000000000371 R11: ffff8800354d1120 R12: 0000000000000000
> [ 28.553517] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
> [ 28.553520] FS: 0000000000000000(0000) GS:ffff880036800000(0000) knlGS:0000000000000000
> [ 28.553522] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 28.553524] CR2: 0000000000000000 CR3: 00000000157a8000 CR4: 00000000000406a0
> [ 28.553528] Stack:
> [ 28.553530] ffff880035b75bd8 ffff880035b7bdf0 ffffffffadd3a94f ffff880035b75000
> [ 28.553535] ffff880015751510 0000000000000b54 ffff880035b7be10 ffff880035b7bd78
> [ 28.553541] 0000000000000000 00007fd735600000 ffff8800354d1000 0000000000000001
> [ 28.553546] Call Trace:
> [ 28.553552] [<ffffffffadd3a94f>] ? __lock_is_held+0x6f/0xa0
> [ 28.553556] [<ffffffffadeee2ea>] khugepaged+0xa1a/0xac0
> [ 28.553560] [<ffffffffadd30bd0>] ? woken_wake_function+0x30/0x30
> [ 28.553563] [<ffffffffadeed8d0>] ? khugepaged_scan_pmd+0xaa0/0xaa0
> [ 28.553568] [<ffffffffadcf9bb2>] kthread+0x132/0x160
> [ 28.553574] [<ffffffffadcf9a80>] ? kthread_unpark+0x80/0x80
> [ 28.553578] [<ffffffffae764c9f>] ret_from_fork+0x3f/0x70
> [ 28.553581] [<ffffffffadcf9a80>] ? kthread_unpark+0x80/0x80
> [ 28.553583] Code: 02 00 00 bb 03 00 00 00 48 83 05 d0 4e b4 02 01 4d 89 e5 48 8b 7d b8 e8 74 5d 87 00 48 83 05 ec 4e b4 02 01 c7 45 c0 00 00 00 00 <49> 8b 14 24 48 89 d0 48 c1 ea 35 48 8b 14 d5 00 00 a2 b0 48 c1
> [ 28.553655] RIP [<ffffffffadeed16b>] khugepaged_scan_pmd+0x33b/0xaa0
> [ 28.553659] RSP <ffff880035b7bd20>
> [ 28.553660] CR2: 0000000000000000
> [ 28.553666] ---[ end trace bb022a4fda57d1e5 ]---
> [ 28.553669] Kernel panic - not syncing: Fatal exception
Seems it should be something like that (untested at moment, please
take a look).
---
From: Cyrill Gorcunov <gorcunov@...nvz.org>
Subject: [PATCH] mm: Fix tracepoint for scanning pages
The page might be NULL so use page_to_pfn in conditional call.
Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
---
include/trace/events/huge_memory.h | 12 ++++++------
mm/huge_memory.c | 6 +++---
2 files changed, 9 insertions(+), 9 deletions(-)
Index: linux-ml.git/include/trace/events/huge_memory.h
===================================================================
--- linux-ml.git.orig/include/trace/events/huge_memory.h
+++ linux-ml.git/include/trace/events/huge_memory.h
@@ -46,10 +46,10 @@ SCAN_STATUS
TRACE_EVENT(mm_khugepaged_scan_pmd,
- TP_PROTO(struct mm_struct *mm, unsigned long pfn, bool writable,
+ TP_PROTO(struct mm_struct *mm, struct page *page, bool writable,
bool referenced, int none_or_zero, int status),
- TP_ARGS(mm, pfn, writable, referenced, none_or_zero, status),
+ TP_ARGS(mm, page, writable, referenced, none_or_zero, status),
TP_STRUCT__entry(
__field(struct mm_struct *, mm)
@@ -62,7 +62,7 @@ TRACE_EVENT(mm_khugepaged_scan_pmd,
TP_fast_assign(
__entry->mm = mm;
- __entry->pfn = pfn;
+ __entry->pfn = page ? page_to_pfn(page) : -1UL;
__entry->writable = writable;
__entry->referenced = referenced;
__entry->none_or_zero = none_or_zero;
@@ -104,10 +104,10 @@ TRACE_EVENT(mm_collapse_huge_page,
TRACE_EVENT(mm_collapse_huge_page_isolate,
- TP_PROTO(unsigned long pfn, int none_or_zero,
+ TP_PROTO(struct page *page, int none_or_zero,
bool referenced, bool writable, int status),
- TP_ARGS(pfn, none_or_zero, referenced, writable, status),
+ TP_ARGS(page, none_or_zero, referenced, writable, status),
TP_STRUCT__entry(
__field(unsigned long, pfn)
@@ -118,7 +118,7 @@ TRACE_EVENT(mm_collapse_huge_page_isolat
),
TP_fast_assign(
- __entry->pfn = pfn;
+ __entry->pfn = page ? page_to_pfn(page) : -1UL;
__entry->none_or_zero = none_or_zero;
__entry->referenced = referenced;
__entry->writable = writable;
Index: linux-ml.git/mm/huge_memory.c
===================================================================
--- linux-ml.git.orig/mm/huge_memory.c
+++ linux-ml.git/mm/huge_memory.c
@@ -2068,7 +2068,7 @@ static int __collapse_huge_page_isolate(
if (likely(writable)) {
if (likely(referenced)) {
result = SCAN_SUCCEED;
- trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero,
+ trace_mm_collapse_huge_page_isolate(page, none_or_zero,
referenced, writable, result);
return 1;
}
@@ -2078,7 +2078,7 @@ static int __collapse_huge_page_isolate(
out:
release_pte_pages(pte, _pte);
- trace_mm_collapse_huge_page_isolate(page_to_pfn(page), none_or_zero,
+ trace_mm_collapse_huge_page_isolate(page, none_or_zero,
referenced, writable, result);
return 0;
}
@@ -2576,7 +2576,7 @@ out_unmap:
collapse_huge_page(mm, address, hpage, vma, node);
}
out:
- trace_mm_khugepaged_scan_pmd(mm, page_to_pfn(page), writable, referenced,
+ trace_mm_khugepaged_scan_pmd(mm, page, writable, referenced,
none_or_zero, result);
return ret;
}
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