* Re: general protection fault in wb_timer_fn
[not found] ` <CACkBjsYwLYLRmX8GpsDpMthagWOjWWrNxqY6ZLNQVr6yx+f5vA@mail.gmail.com>
@ 2021-09-15 7:29 ` Christoph Hellwig
2021-09-15 19:42 ` Yang Shi
0 siblings, 1 reply; 4+ messages in thread
From: Christoph Hellwig @ 2021-09-15 7:29 UTC (permalink / raw)
To: Hao Sun
Cc: Christoph Hellwig, Jens Axboe, linux-block, linux-kernel, linux-mm
On Wed, Sep 15, 2021 at 09:49:49AM +0800, Hao Sun wrote:
> console output: https://paste.ubuntu.com/p/5qHqPXWmCQ/
> kernel config: https://paste.ubuntu.com/p/VsVbFh9ZpQ/
> C reproducer: https://paste.ubuntu.com/p/yrYsn4zpcn/
> Syzlang reproducer: https://paste.ubuntu.com/p/bCWyNyHncJ/
>
> Just tried the C reproducer on the latest Linux kernel (6880fa6c5660
> Linux 5.15-rc1).
> The reproducer still crashed the kernel but with a different backtrace.
Well, that trace looks very much like an issue in the MM truncate code.
Adding the linux-mm list.
>
> IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
> IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
> Bluetooth: hci0: command 0x0409 tx timeout
> ------------[ cut here ]------------
> kernel BUG at fs/buffer.c:1510!
> invalid opcode: 0000 [#1] PREEMPT SMP
> CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.14.0+ #15
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> Workqueue: events delayed_fput
> RIP: 0010:block_invalidatepage+0x27f/0x2a0 -origin/fs/buffer.c:1510
> Code: ff ff e8 b4 07 d7 ff b9 02 00 00 00 be 02 00 00 00 4c 89 ff 48
> c7 c2 40 4e 25 84 e8 2b c2 c4 02 e9 c9 fe ff ff e8 91 07 d7 ff <0f> 0b
> e8 8a 07 d7 ff 0f 0b e8 83 07 d7 ff 48 8d 5d ff e9 57 ff ff
> RSP: 0018:ffffc9000065bb60 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffffea0000670000 RCX: 0000000000000000
> RDX: ffff8880097fa240 RSI: ffffffff81608a9f RDI: ffffea0000670000
> RBP: ffffea0000670000 R08: 0000000000000001 R09: 0000000000000000
> R10: ffffc9000065b9f8 R11: 0000000000000003 R12: ffffffff81608820
> R13: ffffc9000065bc68 R14: 0000000000000000 R15: ffffc9000065bbf0
> FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f4aef93fb08 CR3: 0000000108cf2000 CR4: 0000000000750ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
> do_invalidatepage -origin/mm/truncate.c:157 [inline]
> truncate_cleanup_page+0x15c/0x280 -origin/mm/truncate.c:176
> truncate_inode_pages_range+0x169/0xc30 -origin/mm/truncate.c:325
> kill_bdev.isra.29+0x28/0x30
> blkdev_flush_mapping+0x4c/0x130 -origin/block/bdev.c:658
> blkdev_put_whole+0x54/0x60 -origin/block/bdev.c:689
> blkdev_put+0x6f/0x210 -origin/block/bdev.c:953
> blkdev_close+0x25/0x30 -origin/block/fops.c:459
> __fput+0xdf/0x380 -origin/fs/file_table.c:280
> delayed_fput+0x25/0x40 -origin/fs/file_table.c:308
> process_one_work+0x359/0x850 -origin/kernel/workqueue.c:2297
> worker_thread+0x41/0x4d0 -origin/kernel/workqueue.c:2444
> kthread+0x178/0x1b0 -origin/kernel/kthread.c:319
> ret_from_fork+0x1f/0x30 -origin/arch/x86/entry/entry_64.S:295
> Modules linked in:
> Dumping ftrace buffer:
> (ftrace buffer empty)
> ---[ end trace 9dbb8f58f2109f10 ]---
> RIP: 0010:block_invalidatepage+0x27f/0x2a0 -origin/fs/buffer.c:1510
> Code: ff ff e8 b4 07 d7 ff b9 02 00 00 00 be 02 00 00 00 4c 89 ff 48
> c7 c2 40 4e 25 84 e8 2b c2 c4 02 e9 c9 fe ff ff e8 91 07 d7 ff <0f> 0b
> e8 8a 07 d7 ff 0f 0b e8 83 07 d7 ff 48 8d 5d ff e9 57 ff ff
> RSP: 0018:ffffc9000065bb60 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: ffffea0000670000 RCX: 0000000000000000
> RDX: ffff8880097fa240 RSI: ffffffff81608a9f RDI: ffffea0000670000
> RBP: ffffea0000670000 R08: 0000000000000001 R09: 0000000000000000
> R10: ffffc9000065b9f8 R11: 0000000000000003 R12: ffffffff81608820
> R13: ffffc9000065bc68 R14: 0000000000000000 R15: ffffc9000065bbf0
> FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ff98674f000 CR3: 0000000106b2e000 CR4: 0000000000750ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
---end quoted text---
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: general protection fault in wb_timer_fn
2021-09-15 7:29 ` general protection fault in wb_timer_fn Christoph Hellwig
@ 2021-09-15 19:42 ` Yang Shi
2021-09-16 10:47 ` Hao Sun
0 siblings, 1 reply; 4+ messages in thread
From: Yang Shi @ 2021-09-15 19:42 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Hao Sun, Jens Axboe, linux-block, Linux Kernel Mailing List, Linux MM
On Wed, Sep 15, 2021 at 12:34 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Wed, Sep 15, 2021 at 09:49:49AM +0800, Hao Sun wrote:
> > console output: https://paste.ubuntu.com/p/5qHqPXWmCQ/
> > kernel config: https://paste.ubuntu.com/p/VsVbFh9ZpQ/
> > C reproducer: https://paste.ubuntu.com/p/yrYsn4zpcn/
> > Syzlang reproducer: https://paste.ubuntu.com/p/bCWyNyHncJ/
> >
> > Just tried the C reproducer on the latest Linux kernel (6880fa6c5660
> > Linux 5.15-rc1).
> > The reproducer still crashed the kernel but with a different backtrace.
>
> Well, that trace looks very much like an issue in the MM truncate code.
> Adding the linux-mm list.
The BUG is triggered if it tries to invalidate across pages. But it
hardcoded PAGE_SIZE. The offset passed in by truncate_cleanup_page()
is 0, but the length might be > PAGE_SIZE if it is a compound page. It
might be caused by READ_ONLY_THP_FOR_FS.
Could you please try the below debug patch to dump page details? I saw
your kernel config has DEBUG_VM enabled.
diff --git a/fs/buffer.c b/fs/buffer.c
index ab7573d72dd7..ed7256112c2b 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1507,7 +1507,8 @@ void block_invalidatepage(struct page *page,
unsigned int offset,
/*
* Check for overflow
*/
- BUG_ON(stop > PAGE_SIZE || stop < length);
+ VM_BUG_ON_PAGE((stop > PAGE_SIZE), page);
+ VM_BUG_ON_PAGE((stop < length), page);
head = page_buffers(page);
bh = head;
If my speculation is correct, I think the below patch should be able
to fix this issue.
diff --git a/fs/buffer.c b/fs/buffer.c
index ab7573d72dd7..18428cee59af 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1507,7 +1507,7 @@ void block_invalidatepage(struct page *page,
unsigned int offset,
/*
* Check for overflow
*/
- BUG_ON(stop > PAGE_SIZE || stop < length);
+ BUG_ON(stop > thp_size(page) || stop < length);
head = page_buffers(page);
bh = head;
>
> >
> > IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
> > IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
> > Bluetooth: hci0: command 0x0409 tx timeout
> > ------------[ cut here ]------------
> > kernel BUG at fs/buffer.c:1510!
> > invalid opcode: 0000 [#1] PREEMPT SMP
> > CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.14.0+ #15
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> > rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
> > Workqueue: events delayed_fput
> > RIP: 0010:block_invalidatepage+0x27f/0x2a0 -origin/fs/buffer.c:1510
> > Code: ff ff e8 b4 07 d7 ff b9 02 00 00 00 be 02 00 00 00 4c 89 ff 48
> > c7 c2 40 4e 25 84 e8 2b c2 c4 02 e9 c9 fe ff ff e8 91 07 d7 ff <0f> 0b
> > e8 8a 07 d7 ff 0f 0b e8 83 07 d7 ff 48 8d 5d ff e9 57 ff ff
> > RSP: 0018:ffffc9000065bb60 EFLAGS: 00010293
> > RAX: 0000000000000000 RBX: ffffea0000670000 RCX: 0000000000000000
> > RDX: ffff8880097fa240 RSI: ffffffff81608a9f RDI: ffffea0000670000
> > RBP: ffffea0000670000 R08: 0000000000000001 R09: 0000000000000000
> > R10: ffffc9000065b9f8 R11: 0000000000000003 R12: ffffffff81608820
> > R13: ffffc9000065bc68 R14: 0000000000000000 R15: ffffc9000065bbf0
> > FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007f4aef93fb08 CR3: 0000000108cf2000 CR4: 0000000000750ef0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > PKRU: 55555554
> > Call Trace:
> > do_invalidatepage -origin/mm/truncate.c:157 [inline]
> > truncate_cleanup_page+0x15c/0x280 -origin/mm/truncate.c:176
> > truncate_inode_pages_range+0x169/0xc30 -origin/mm/truncate.c:325
> > kill_bdev.isra.29+0x28/0x30
> > blkdev_flush_mapping+0x4c/0x130 -origin/block/bdev.c:658
> > blkdev_put_whole+0x54/0x60 -origin/block/bdev.c:689
> > blkdev_put+0x6f/0x210 -origin/block/bdev.c:953
> > blkdev_close+0x25/0x30 -origin/block/fops.c:459
> > __fput+0xdf/0x380 -origin/fs/file_table.c:280
> > delayed_fput+0x25/0x40 -origin/fs/file_table.c:308
> > process_one_work+0x359/0x850 -origin/kernel/workqueue.c:2297
> > worker_thread+0x41/0x4d0 -origin/kernel/workqueue.c:2444
> > kthread+0x178/0x1b0 -origin/kernel/kthread.c:319
> > ret_from_fork+0x1f/0x30 -origin/arch/x86/entry/entry_64.S:295
> > Modules linked in:
> > Dumping ftrace buffer:
> > (ftrace buffer empty)
> > ---[ end trace 9dbb8f58f2109f10 ]---
> > RIP: 0010:block_invalidatepage+0x27f/0x2a0 -origin/fs/buffer.c:1510
> > Code: ff ff e8 b4 07 d7 ff b9 02 00 00 00 be 02 00 00 00 4c 89 ff 48
> > c7 c2 40 4e 25 84 e8 2b c2 c4 02 e9 c9 fe ff ff e8 91 07 d7 ff <0f> 0b
> > e8 8a 07 d7 ff 0f 0b e8 83 07 d7 ff 48 8d 5d ff e9 57 ff ff
> > RSP: 0018:ffffc9000065bb60 EFLAGS: 00010293
> > RAX: 0000000000000000 RBX: ffffea0000670000 RCX: 0000000000000000
> > RDX: ffff8880097fa240 RSI: ffffffff81608a9f RDI: ffffea0000670000
> > RBP: ffffea0000670000 R08: 0000000000000001 R09: 0000000000000000
> > R10: ffffc9000065b9f8 R11: 0000000000000003 R12: ffffffff81608820
> > R13: ffffc9000065bc68 R14: 0000000000000000 R15: ffffc9000065bbf0
> > FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007ff98674f000 CR3: 0000000106b2e000 CR4: 0000000000750ef0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > PKRU: 55555554
> ---end quoted text---
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: general protection fault in wb_timer_fn
2021-09-15 19:42 ` Yang Shi
@ 2021-09-16 10:47 ` Hao Sun
2021-09-16 20:18 ` Yang Shi
0 siblings, 1 reply; 4+ messages in thread
From: Hao Sun @ 2021-09-16 10:47 UTC (permalink / raw)
To: Yang Shi
Cc: Christoph Hellwig, Jens Axboe, linux-block,
Linux Kernel Mailing List, Linux MM
> The BUG is triggered if it tries to invalidate across pages. But it
> hardcoded PAGE_SIZE. The offset passed in by truncate_cleanup_page()
> is 0, but the length might be > PAGE_SIZE if it is a compound page. It
> might be caused by READ_ONLY_THP_FOR_FS.
>
> Could you please try the below debug patch to dump page details? I saw
> your kernel config has DEBUG_VM enabled.
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index ab7573d72dd7..ed7256112c2b 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1507,7 +1507,8 @@ void block_invalidatepage(struct page *page,
> unsigned int offset,
> /*
> * Check for overflow
> */
> - BUG_ON(stop > PAGE_SIZE || stop < length);
> + VM_BUG_ON_PAGE((stop > PAGE_SIZE), page);
> + VM_BUG_ON_PAGE((stop < length), page);
>
> head = page_buffers(page);
> bh = head;
>
Just patched it.
The following log was printed after executing the C reproducer.
IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
Bluetooth: hci0: command 0x0409 tx timeout
Bluetooth: hci0: command 0x041b tx timeout
Bluetooth: hci0: command 0x040f tx timeout
Bluetooth: hci0: command 0x0419 tx timeout
page:ffffea00009c0000 refcount:514 mapcount:0 mapping:ffff8881060db7b0
index:0x0 pfn:0x27000
head:ffffea00009c0000 order:9 compound_mapcount:0 compound_pincount:0
memcg:ffff8880118bc000
aops:def_blk_aops ino:fa00000
flags: 0xfff00000012037(locked|referenced|uptodate|lru|active|private|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000012037 ffffea00009491c8 ffff888010c7d030 ffff8881060db7b0
raw: 0000000000000000 ffff888025d10658 00000202ffffffff ffff8880118bc000
page dumped because: VM_BUG_ON_PAGE((stop > ((1UL) << 12)))
page_owner tracks the page as allocated
page last allocated via order 9, migratetype Movable, gfp_mask
0x13c24ca(GFP_TRANSHUGE|__GFP_THISNODE), pid 35, ts 579054356699,
free_ts 543915753195
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook mm/page_alloc.c:2418 [inline]
prep_new_page+0x1a5/0x240 mm/page_alloc.c:2424
get_page_from_freelist+0x1f10/0x3b70 mm/page_alloc.c:4153
__alloc_pages+0x306/0x6e0 mm/page_alloc.c:5375
__alloc_pages_node include/linux/gfp.h:570 [inline]
khugepaged_alloc_page+0xa0/0x170 mm/khugepaged.c:881
collapse_file+0x20a/0x45f0 mm/khugepaged.c:1655
khugepaged_scan_file mm/khugepaged.c:2051 [inline]
khugepaged_scan_mm_slot mm/khugepaged.c:2146 [inline]
khugepaged_do_scan mm/khugepaged.c:2230 [inline]
khugepaged+0x2e65/0x5c50 mm/khugepaged.c:2275
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1338 [inline]
free_pcp_prepare+0x412/0x900 mm/page_alloc.c:1389
free_unref_page_prepare mm/page_alloc.c:3315 [inline]
free_unref_page+0x19/0x580 mm/page_alloc.c:3394
release_pages+0x87f/0x2920 mm/swap.c:926
tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
tlb_flush_mmu+0x8d/0x610 mm/mmu_gather.c:249
tlb_finish_mmu+0x93/0x3c0 mm/mmu_gather.c:340
unmap_region+0x27f/0x350 mm/mmap.c:2653
__do_munmap+0xabc/0x11e0 mm/mmap.c:2884
do_munmap mm/mmap.c:2895 [inline]
munmap_vma_range mm/mmap.c:603 [inline]
mmap_region+0x2c4/0x1340 mm/mmap.c:1742
do_mmap+0x7f5/0xe60 mm/mmap.c:1575
vm_mmap_pgoff+0x1b7/0x290 mm/util.c:519
ksys_mmap_pgoff+0x49f/0x620 mm/mmap.c:1624
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
------------[ cut here ]------------
kernel BUG at fs/buffer.c:1511!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 2954 Comm: kworker/1:2 Not tainted 5.15.0-rc1+ #4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Workqueue: events delayed_fput
RIP: 0010:block_invalidatepage+0x599/0x680 fs/buffer.c:1511
Code: 0f 0b e8 9a 6b 9c ff 31 f6 4c 89 e7 e8 10 d7 bf ff e9 df fe ff
ff e8 86 6b 9c ff 48 c7 c6 00 4e 9a 89 4c 89 e7 e8 c7 16 d0 ff <0f> 0b
e8 70 6b 9c ff 48 c7 c6 60 4e 9a 89 4c 89 e7 e8 b1 16 d0 ff
RSP: 0018:ffffc9000e9078b8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888100bd9c80
RDX: 0000000000000000 RSI: ffff888100bd9c80 RDI: 0000000000000002
RBP: 0000000000000000 R08: ffffffff81d9e369 R09: 000000000000ffff
R10: 0000000000000003 R11: ffffed1026b83f53 R12: ffffea00009c0000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000200000
FS: 0000000000000000(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffde41e8960 CR3: 0000000019cef000 CR4: 0000000000350ee0
Call Trace:
do_invalidatepage mm/truncate.c:157 [inline]
truncate_cleanup_page+0x3e4/0x620 mm/truncate.c:176
truncate_inode_pages_range+0x26c/0x1910 mm/truncate.c:325
kill_bdev.isra.0+0x5f/0x80 block/bdev.c:77
blkdev_flush_mapping+0xdf/0x2e0 block/bdev.c:658
blkdev_put_whole+0xe8/0x110 block/bdev.c:689
blkdev_put+0x23c/0x6f0 block/bdev.c:953
blkdev_close+0x8d/0xb0 block/fops.c:459
__fput+0x288/0x9f0 fs/file_table.c:280
delayed_fput+0x56/0x70 fs/file_table.c:308
process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
worker_thread+0x90/0xed0 kernel/workqueue.c:2444
kthread+0x3e5/0x4d0 kernel/kthread.c:319
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Modules linked in:
Dumping ftrace buffer:
(ftrace buffer empty)
---[ end trace 77cfca54575c5255 ]---
RIP: 0010:block_invalidatepage+0x599/0x680 fs/buffer.c:1511
Code: 0f 0b e8 9a 6b 9c ff 31 f6 4c 89 e7 e8 10 d7 bf ff e9 df fe ff
ff e8 86 6b 9c ff 48 c7 c6 00 4e 9a 89 4c 89 e7 e8 c7 16 d0 ff <0f> 0b
e8 70 6b 9c ff 48 c7 c6 60 4e 9a 89 4c 89 e7 e8 b1 16 d0 ff
RSP: 0018:ffffc9000e9078b8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888100bd9c80
RDX: 0000000000000000 RSI: ffff888100bd9c80 RDI: 0000000000000002
RBP: 0000000000000000 R08: ffffffff81d9e369 R09: 000000000000ffff
R10: 0000000000000003 R11: ffffed1026b83f53 R12: ffffea00009c0000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000200000
FS: 0000000000000000(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f78dffb7ef8 CR3: 000000001f2ef000 CR4: 0000000000350ee0
> If my speculation is correct, I think the below patch should be able
> to fix this issue.
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index ab7573d72dd7..18428cee59af 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1507,7 +1507,7 @@ void block_invalidatepage(struct page *page,
> unsigned int offset,
> /*
> * Check for overflow
> */
> - BUG_ON(stop > PAGE_SIZE || stop < length);
> + BUG_ON(stop > thp_size(page) || stop < length);
>
> head = page_buffers(page);
> bh = head;
>
Yes, the C reproducer can not crash the kernel anymore after patching
the above code.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: general protection fault in wb_timer_fn
2021-09-16 10:47 ` Hao Sun
@ 2021-09-16 20:18 ` Yang Shi
0 siblings, 0 replies; 4+ messages in thread
From: Yang Shi @ 2021-09-16 20:18 UTC (permalink / raw)
To: Hao Sun, Matthew Wilcox, Hugh Dickins
Cc: Christoph Hellwig, Jens Axboe, linux-block,
Linux Kernel Mailing List, Linux MM
On Thu, Sep 16, 2021 at 3:47 AM Hao Sun <sunhao.th@gmail.com> wrote:
>
> > The BUG is triggered if it tries to invalidate across pages. But it
> > hardcoded PAGE_SIZE. The offset passed in by truncate_cleanup_page()
> > is 0, but the length might be > PAGE_SIZE if it is a compound page. It
> > might be caused by READ_ONLY_THP_FOR_FS.
> >
> > Could you please try the below debug patch to dump page details? I saw
> > your kernel config has DEBUG_VM enabled.
> >
> > diff --git a/fs/buffer.c b/fs/buffer.c
> > index ab7573d72dd7..ed7256112c2b 100644
> > --- a/fs/buffer.c
> > +++ b/fs/buffer.c
> > @@ -1507,7 +1507,8 @@ void block_invalidatepage(struct page *page,
> > unsigned int offset,
> > /*
> > * Check for overflow
> > */
> > - BUG_ON(stop > PAGE_SIZE || stop < length);
> > + VM_BUG_ON_PAGE((stop > PAGE_SIZE), page);
> > + VM_BUG_ON_PAGE((stop < length), page);
> >
> > head = page_buffers(page);
> > bh = head;
> >
>
> Just patched it.
> The following log was printed after executing the C reproducer.
>
> IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
> IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
> Bluetooth: hci0: command 0x0409 tx timeout
> Bluetooth: hci0: command 0x041b tx timeout
> Bluetooth: hci0: command 0x040f tx timeout
> Bluetooth: hci0: command 0x0419 tx timeout
> page:ffffea00009c0000 refcount:514 mapcount:0 mapping:ffff8881060db7b0
> index:0x0 pfn:0x27000
> head:ffffea00009c0000 order:9 compound_mapcount:0 compound_pincount:0
> memcg:ffff8880118bc000
> aops:def_blk_aops ino:fa00000
> flags: 0xfff00000012037(locked|referenced|uptodate|lru|active|private|head|node=0|zone=1|lastcpupid=0x7ff)
> raw: 00fff00000012037 ffffea00009491c8 ffff888010c7d030 ffff8881060db7b0
> raw: 0000000000000000 ffff888025d10658 00000202ffffffff ffff8880118bc000
> page dumped because: VM_BUG_ON_PAGE((stop > ((1UL) << 12)))
> page_owner tracks the page as allocated
> page last allocated via order 9, migratetype Movable, gfp_mask
> 0x13c24ca(GFP_TRANSHUGE|__GFP_THISNODE), pid 35, ts 579054356699,
> free_ts 543915753195
> set_page_owner include/linux/page_owner.h:31 [inline]
> post_alloc_hook mm/page_alloc.c:2418 [inline]
> prep_new_page+0x1a5/0x240 mm/page_alloc.c:2424
> get_page_from_freelist+0x1f10/0x3b70 mm/page_alloc.c:4153
> __alloc_pages+0x306/0x6e0 mm/page_alloc.c:5375
> __alloc_pages_node include/linux/gfp.h:570 [inline]
> khugepaged_alloc_page+0xa0/0x170 mm/khugepaged.c:881
> collapse_file+0x20a/0x45f0 mm/khugepaged.c:1655
> khugepaged_scan_file mm/khugepaged.c:2051 [inline]
> khugepaged_scan_mm_slot mm/khugepaged.c:2146 [inline]
> khugepaged_do_scan mm/khugepaged.c:2230 [inline]
> khugepaged+0x2e65/0x5c50 mm/khugepaged.c:2275
> kthread+0x3e5/0x4d0 kernel/kthread.c:319
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> page last free stack trace:
> reset_page_owner include/linux/page_owner.h:24 [inline]
> free_pages_prepare mm/page_alloc.c:1338 [inline]
> free_pcp_prepare+0x412/0x900 mm/page_alloc.c:1389
> free_unref_page_prepare mm/page_alloc.c:3315 [inline]
> free_unref_page+0x19/0x580 mm/page_alloc.c:3394
> release_pages+0x87f/0x2920 mm/swap.c:926
> tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
> tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
> tlb_flush_mmu+0x8d/0x610 mm/mmu_gather.c:249
> tlb_finish_mmu+0x93/0x3c0 mm/mmu_gather.c:340
> unmap_region+0x27f/0x350 mm/mmap.c:2653
> __do_munmap+0xabc/0x11e0 mm/mmap.c:2884
> do_munmap mm/mmap.c:2895 [inline]
> munmap_vma_range mm/mmap.c:603 [inline]
> mmap_region+0x2c4/0x1340 mm/mmap.c:1742
> do_mmap+0x7f5/0xe60 mm/mmap.c:1575
> vm_mmap_pgoff+0x1b7/0x290 mm/util.c:519
> ksys_mmap_pgoff+0x49f/0x620 mm/mmap.c:1624
> do_syscall_x64 arch/x86/entry/common.c:50 [inline]
> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> ------------[ cut here ]------------
> kernel BUG at fs/buffer.c:1511!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 2954 Comm: kworker/1:2 Not tainted 5.15.0-rc1+ #4
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.13.0-1ubuntu1.1 04/01/2014
> Workqueue: events delayed_fput
> RIP: 0010:block_invalidatepage+0x599/0x680 fs/buffer.c:1511
> Code: 0f 0b e8 9a 6b 9c ff 31 f6 4c 89 e7 e8 10 d7 bf ff e9 df fe ff
> ff e8 86 6b 9c ff 48 c7 c6 00 4e 9a 89 4c 89 e7 e8 c7 16 d0 ff <0f> 0b
> e8 70 6b 9c ff 48 c7 c6 60 4e 9a 89 4c 89 e7 e8 b1 16 d0 ff
> RSP: 0018:ffffc9000e9078b8 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888100bd9c80
> RDX: 0000000000000000 RSI: ffff888100bd9c80 RDI: 0000000000000002
> RBP: 0000000000000000 R08: ffffffff81d9e369 R09: 000000000000ffff
> R10: 0000000000000003 R11: ffffed1026b83f53 R12: ffffea00009c0000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000200000
> FS: 0000000000000000(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007ffde41e8960 CR3: 0000000019cef000 CR4: 0000000000350ee0
> Call Trace:
> do_invalidatepage mm/truncate.c:157 [inline]
> truncate_cleanup_page+0x3e4/0x620 mm/truncate.c:176
> truncate_inode_pages_range+0x26c/0x1910 mm/truncate.c:325
> kill_bdev.isra.0+0x5f/0x80 block/bdev.c:77
> blkdev_flush_mapping+0xdf/0x2e0 block/bdev.c:658
> blkdev_put_whole+0xe8/0x110 block/bdev.c:689
> blkdev_put+0x23c/0x6f0 block/bdev.c:953
> blkdev_close+0x8d/0xb0 block/fops.c:459
> __fput+0x288/0x9f0 fs/file_table.c:280
> delayed_fput+0x56/0x70 fs/file_table.c:308
> process_one_work+0x9df/0x16d0 kernel/workqueue.c:2297
> worker_thread+0x90/0xed0 kernel/workqueue.c:2444
> kthread+0x3e5/0x4d0 kernel/kthread.c:319
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
> Modules linked in:
> Dumping ftrace buffer:
> (ftrace buffer empty)
> ---[ end trace 77cfca54575c5255 ]---
> RIP: 0010:block_invalidatepage+0x599/0x680 fs/buffer.c:1511
> Code: 0f 0b e8 9a 6b 9c ff 31 f6 4c 89 e7 e8 10 d7 bf ff e9 df fe ff
> ff e8 86 6b 9c ff 48 c7 c6 00 4e 9a 89 4c 89 e7 e8 c7 16 d0 ff <0f> 0b
> e8 70 6b 9c ff 48 c7 c6 60 4e 9a 89 4c 89 e7 e8 b1 16 d0 ff
> RSP: 0018:ffffc9000e9078b8 EFLAGS: 00010246
> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888100bd9c80
> RDX: 0000000000000000 RSI: ffff888100bd9c80 RDI: 0000000000000002
> RBP: 0000000000000000 R08: ffffffff81d9e369 R09: 000000000000ffff
> R10: 0000000000000003 R11: ffffed1026b83f53 R12: ffffea00009c0000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000200000
> FS: 0000000000000000(0000) GS:ffff888135c00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f78dffb7ef8 CR3: 000000001f2ef000 CR4: 0000000000350ee0
>
>
> > If my speculation is correct, I think the below patch should be able
> > to fix this issue.
> >
> > diff --git a/fs/buffer.c b/fs/buffer.c
> > index ab7573d72dd7..18428cee59af 100644
> > --- a/fs/buffer.c
> > +++ b/fs/buffer.c
> > @@ -1507,7 +1507,7 @@ void block_invalidatepage(struct page *page,
> > unsigned int offset,
> > /*
> > * Check for overflow
> > */
> > - BUG_ON(stop > PAGE_SIZE || stop < length);
> > + BUG_ON(stop > thp_size(page) || stop < length);
> >
> > head = page_buffers(page);
> > bh = head;
> >
>")
> Yes, the C reproducer can not crash the kernel anymore after patching
> the above code.
Thank you for running the test. This does prove my speculation. It
seems commit eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint
on file-backed THPs") opens much more cases for file THPs.
It seems your test case opens null block device and mmaps with
PROT_EXEC. This is why the THP is collapsed.
The above fix is kind of ad-hoc. The further investigation shows
bigger problem in invalidatepage(). All the implementations are *NOT*
THP aware and hardcoded PAGE_SIZE. Some triggers BUG(), like
block_invalidatepage(), some just returns error if length is >
PAGE_SIZE.
We could convert PAGE_SIZE to thp_size(), but it seems not enough
since the current implementations just invalidate one subpage
(typically head page), but it is not enough since other subpages may
have private too because PG_private is per subpage so there may be
multiple subpages have private IIUC. This may cause the THP not
splittable and reclaimable since the extra refcount pins from private
of subpages prevent this.
I could submit a patch to close the BUG() for now since more work
definitely needs to be done to make all the things right. However, how
to fix this may have conflicts with Willy's page folio work, so this
may not happen at any time soon.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-09-16 20:18 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-09-15 7:29 ` general protection fault in wb_timer_fn Christoph Hellwig
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