Re: [PATCH] mm/mlock: fix BUG_ON unlocked page for nolinear VMAs
From: Vlastimil Babka
Date: Wed Dec 18 2013 - 03:54:28 EST
On 12/17/2013 09:05 AM, Wanpeng Li wrote:
objrmap doesn't work for nonlinear VMAs because the assumption that offset-into-file
correlates with offset-into-virtual-addresses does not hold. Hence what
try_to_unmap_cluster does is a mini "virtual scan" of each nonlinear VMA which maps
the file to which the target page belongs. If vma locked, mlock the pages in the
cluster, rather than unmapping them. However, not all pages are guarantee page
locked instead of the check page. This patch fix the BUG by just confirm check page
hold page lock instead of all pages in the virtual scan window against nolinear VMAs.
This may fix the symptom, but I don't understand from the description
why in this case is it ok not to have page locked for mlock_vma_page(),
while in the other cases it's not ok.
[ 253.869145] kernel BUG at mm/mlock.c:82!
[ 253.869549] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 253.870098] Dumping ftrace buffer:
[ 253.870098] (ftrace buffer empty)
[ 253.870098] Modules linked in:
[ 253.870098] CPU: 10 PID: 9162 Comm: trinity-child75 Tainted: G W 3.13.0-rc4-next-20131216-sasha-00011-g5f105ec-dirty #4137
[ 253.873310] task: ffff8800c98cb000 ti: ffff8804d34e8000 task.ti: ffff8804d34e8000
[ 253.873310] RIP: 0010:[<ffffffff81281f28>] [<ffffffff81281f28>] mlock_vma_page+0x18/0xc0
[ 253.873310] RSP: 0000:ffff8804d34e99e8 EFLAGS: 00010246
[ 253.873310] RAX: 006fffff8038002c RBX: ffffea00474944c0 RCX: ffff880807636000
[ 253.873310] RDX: ffffea0000000000 RSI: 00007f17a9bca000 RDI: ffffea00474944c0
[ 253.873310] RBP: ffff8804d34e99f8 R08: ffff880807020000 R09: 0000000000000000
[ 253.873310] R10: 0000000000000001 R11: 0000000000002000 R12: 00007f17a9bca000
[ 253.873310] R13: ffffea00474944c0 R14: 00007f17a9be0000 R15: ffff880807020000
[ 253.873310] FS: 00007f17aa31a700(0000) GS:ffff8801c9c00000(0000) knlGS:0000000000000000
[ 253.873310] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 253.873310] CR2: 00007f17a94fa000 CR3: 00000004d3b02000 CR4: 00000000000006e0
[ 253.873310] DR0: 00007f17a74ca000 DR1: 0000000000000000 DR2: 0000000000000000
[ 253.873310] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
[ 253.873310] Stack:
[ 253.873310] 0000000b3de28067 ffff880b3de28e50 ffff8804d34e9aa8 ffffffff8128bc31
[ 253.873310] 0000000000000301 ffffea0011850220 ffff8809a4039000 ffffea0011850238
[ 253.873310] ffff8804d34e9aa8 ffff880807636060 0000000000000001 ffff880807636348
[ 253.873310] Call Trace:
[ 253.873310] [<ffffffff8128bc31>] try_to_unmap_cluster+0x1c1/0x340
[ 253.873310] [<ffffffff8128c60a>] try_to_unmap_file+0x20a/0x2e0
[ 253.873310] [<ffffffff8128c7b3>] try_to_unmap+0x73/0x90
[ 253.873310] [<ffffffff812b526d>] __unmap_and_move+0x18d/0x250
[ 253.873310] [<ffffffff812b53e9>] unmap_and_move+0xb9/0x180
[ 253.873310] [<ffffffff812b559b>] migrate_pages+0xeb/0x2f0
[ 253.873310] [<ffffffff812a0660>] ? queue_pages_pte_range+0x1a0/0x1a0
[ 253.873310] [<ffffffff812a193c>] migrate_to_node+0x9c/0xc0
[ 253.873310] [<ffffffff812a30b8>] do_migrate_pages+0x1b8/0x240
[ 253.873310] [<ffffffff812a3456>] SYSC_migrate_pages+0x316/0x380
[ 253.873310] [<ffffffff812a31ec>] ? SYSC_migrate_pages+0xac/0x380
[ 253.873310] [<ffffffff811763c6>] ? vtime_account_user+0x96/0xb0
[ 253.873310] [<ffffffff812a34ce>] SyS_migrate_pages+0xe/0x10
[ 253.873310] [<ffffffff843c4990>] tracesys+0xdd/0xe2
[ 253.873310] Code: 0f 1f 00 65 48 ff 04 25 10 25 1d 00 48 83 c4 08
5b c9 c3 55 48 89 e5 53 48 83 ec 08 66 66 66 66 90 48 8b 07 48 89 fb
a8 01 75 10 <0f> 0b 66 0f 1f 44 00 00 eb fe 66 0f 1f 44 00 00 f0 0f ba
2f 15
[ 253.873310] RIP [<ffffffff81281f28>] mlock_vma_page+0x18/0xc0
[ 253.873310] RSP <ffff8804d34e99e8>
[ 253.904194] ---[ end trace be59c4a7f8edab3f ]---
Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 2 +-
mm/internal.h | 4 ++--
mm/ksm.c | 2 +-
mm/memory.c | 2 +-
mm/mlock.c | 5 +++--
mm/rmap.c | 4 ++--
6 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 33a5dc4..7a15b04 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1264,7 +1264,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
if (page->mapping && trylock_page(page)) {
lru_add_drain();
if (page->mapping)
- mlock_vma_page(page);
+ mlock_vma_page(page, true);
unlock_page(page);
}
}
diff --git a/mm/internal.h b/mm/internal.h
index a85a3ab..4ea2d4e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -192,7 +192,7 @@ static inline int mlocked_vma_newpage(struct vm_area_struct *vma,
/*
* must be called with vma's mmap_sem held for read or write, and page locked.
*/
-extern void mlock_vma_page(struct page *page);
+extern void mlock_vma_page(struct page *page, bool check_page);
extern unsigned int munlock_vma_page(struct page *page);
/*
@@ -236,7 +236,7 @@ static inline int mlocked_vma_newpage(struct vm_area_struct *v, struct page *p)
return 0;
}
static inline void clear_page_mlock(struct page *page) { }
-static inline void mlock_vma_page(struct page *page) { }
+static inline void mlock_vma_page(struct page *page, bool check_page) { }
static inline void mlock_migrate_page(struct page *new, struct page *old) { }
#endif /* !CONFIG_MMU */
diff --git a/mm/ksm.c b/mm/ksm.c
index 175fff7..ec36f04 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1064,7 +1064,7 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
if (!PageMlocked(kpage)) {
unlock_page(page);
lock_page(kpage);
- mlock_vma_page(kpage);
+ mlock_vma_page(kpage, true);
page = kpage; /* for final unlock */
}
}
diff --git a/mm/memory.c b/mm/memory.c
index cf6098c..a41df6a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1602,7 +1602,7 @@ split_fallthrough:
* know the page is still mapped, we don't even
* need to check for file-cache page truncation.
*/
- mlock_vma_page(page);
+ mlock_vma_page(page, true);
unlock_page(page);
}
}
diff --git a/mm/mlock.c b/mm/mlock.c
index d480cd6..c395ec5 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -77,9 +77,10 @@ void clear_page_mlock(struct page *page)
* Mark page as mlocked if not already.
* If page on LRU, isolate and putback to move to unevictable list.
*/
-void mlock_vma_page(struct page *page)
+void mlock_vma_page(struct page *page, bool check_page)
{
- BUG_ON(!PageLocked(page));
+ if (check_page)
+ BUG_ON(!PageLocked(page));
if (!TestSetPageMlocked(page)) {
mod_zone_page_state(page_zone(page), NR_MLOCK,
diff --git a/mm/rmap.c b/mm/rmap.c
index 55c8b8d..79d456f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1297,7 +1297,7 @@ out_mlock:
*/
if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
if (vma->vm_flags & VM_LOCKED) {
- mlock_vma_page(page);
+ mlock_vma_page(page, true);
ret = SWAP_MLOCK;
}
up_read(&vma->vm_mm->mmap_sem);
@@ -1385,7 +1385,7 @@ static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
BUG_ON(!page || PageAnon(page));
if (locked_vma) {
- mlock_vma_page(page); /* no-op if already mlocked */
+ mlock_vma_page(page, page == check_page); /* no-op if already mlocked */
if (page == check_page)
ret = SWAP_MLOCK;
continue; /* don't unmap */
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/