Re: mm: WARNING in __delete_from_page_cache

[Williams, Dan J]

On Tue, 2016-01-26 at 14:36 +-0100, Jan Kara wrote:
+AD4- On Tue 26-01-16 07:54:56, Matthew Wilcox wrote:
+AD4- +AD4- On Tue, Jan 26, 2016 at 03:42:34AM +-0000, Williams, Dan J wrote:
+AD4- +AD4- +AD4- +AEAAQA- -2907,7 +-2912,12 +AEAAQA- extern void replace+AF8-mount+AF8-options(struct
+AD4- +AD4- +AD4- super+AF8-block +ACo-sb, char +ACo-options)+ADs-
+AD4- +AD4- +AD4- +AKA-
+AD4- +AD4- +AD4- +AKA-static inline bool io+AF8-is+AF8-direct(struct file +ACo-filp)
+AD4- +AD4- +AD4- +AKAAew-
+AD4- +AD4- +AD4- -	return (filp-+AD4-f+AF8-flags +ACY- O+AF8-DIRECT) +AHwAfA-
+AD4- +AD4- +AD4- IS+AF8-DAX(file+AF8-inode(filp))+ADs-
+AD4- +AD4- 
+AD4- +AD4- I think this should just be a one-liner:
+AD4- +AD4- 
+AD4- +AD4- -	return (filp-+AD4-f+AF8-flags +ACY- O+AF8-DIRECT) +AHwAfA-
+AD4- +AD4- IS+AF8-DAX(file+AF8-inode(filp))+ADs-
+AD4- +AD4- +-	return (filp-+AD4-f+AF8-flags +ACY- O+AF8-DIRECT) +AHwAfA- IS+AF8-DAX(filp-
+AD4- +AD4- +AD4-f+AF8-mapping-+AD4-host)+ADs-
+AD4- +AD4- 
+AD4- +AD4- This does the right thing for block device inodes and filesystem
+AD4- +AD4- inodes.
+AD4- +AD4- (see the opening stanzas of +AF8AXw-dax+AF8-fault for an example).
+AD4- 
+AD4- Ah, right. This looks indeed better.
+AD4- 


Oh, yeah, looks good.

8+ADw----- (git am --scissors)
Subject: fs, block: force direct-I/O for dax-enabled block devices

From: Dan Williams +ADw-dan.j.williams+AEA-intel.com+AD4-

Similar to the file I/O path, re-direct all I/O to the DAX path for I/O
to a block-device special file.+AKAAoA-Both regular files and device special
files can use the common filp-+AD4-f+AF8-mapping-+AD4-host lookup to determing is
DAX is enabled.

Otherwise, we confuse the DAX code that does not expect to find live
data in the page cache:

+AKAAoACgAKA-------------+AFs- cut here +AF0-------------
+AKAAoACgAKA-WARNING: CPU: 0 PID: 7676 at mm/filemap.c:217
+AKAAoACgAKAAXwBf-delete+AF8-from+AF8-page+AF8-cache+-0x9f6/0xb60()
+AKAAoACgAKA-Modules linked in:
+AKAAoACgAKA-CPU: 0 PID: 7676 Comm: a.out Not tainted 4.4.0+- +ACM-276
+AKAAoACgAKA-Hardware name: QEMU Standard PC (i440FX +- PIIX, 1996), BIOS Bochs 01/01/2011
+AKAAoACgAKAAoA-00000000ffffffff ffff88006d3f7738 ffffffff82999e2d 0000000000000000
+AKAAoACgAKAAoA-ffff8800620a0000 ffffffff86473d20 ffff88006d3f7778 ffffffff81352089
+AKAAoACgAKAAoA-ffffffff81658d36 ffffffff86473d20 00000000000000d9 ffffea0000009d60
+AKAAoACgAKA-Call Trace:
+AKAAoACgAKAAoABbADwAoACgAKAAoACg-inline+AKAAoACgAKAAoAA+AF0- +AF8AXw-dump+AF8-stack lib/dump+AF8-stack.c:15
+AKAAoACgAKAAoABbADw-ffffffff82999e2d+AD4AXQ- dump+AF8-stack+-0x6f/0xa2 lib/dump+AF8-stack.c:50
+AKAAoACgAKAAoABbADw-ffffffff81352089+AD4AXQ- warn+AF8-slowpath+AF8-common+-0xd9/0x140 kernel/panic.c:482
+AKAAoACgAKAAoABbADw-ffffffff813522b9+AD4AXQ- warn+AF8-slowpath+AF8-null+-0x29/0x30 kernel/panic.c:515
+AKAAoACgAKAAoABbADw-ffffffff81658d36+AD4AXQ- +AF8AXw-delete+AF8-from+AF8-page+AF8-cache+-0x9f6/0xb60 mm/filemap.c:217
+AKAAoACgAKAAoABbADw-ffffffff81658fb2+AD4AXQ- delete+AF8-from+AF8-page+AF8-cache+-0x112/0x200 mm/filemap.c:244
+AKAAoACgAKAAoABbADw-ffffffff818af369+AD4AXQ- +AF8AXw-dax+AF8-fault+-0x859/0x1800 fs/dax.c:487
+AKAAoACgAKAAoABbADw-ffffffff8186f4f6+AD4AXQ- blkdev+AF8-dax+AF8-fault+-0x26/0x30 fs/block+AF8-dev.c:1730
+AKAAoACgAKAAoABbADwAoACgAKAAoACg-inline+AKAAoACgAKAAoAA+AF0- wp+AF8-pfn+AF8-shared mm/memory.c:2208
+AKAAoACgAKAAoABbADw-ffffffff816e9145+AD4AXQ- do+AF8-wp+AF8-page+-0xc85/0x14f0 mm/memory.c:2307
+AKAAoACgAKAAoABbADwAoACgAKAAoACg-inline+AKAAoACgAKAAoAA+AF0- handle+AF8-pte+AF8-fault mm/memory.c:3323
+AKAAoACgAKAAoABbADwAoACgAKAAoACg-inline+AKAAoACgAKAAoAA+AF0- +AF8AXw-handle+AF8-mm+AF8-fault mm/memory.c:3417
+AKAAoACgAKAAoABbADw-ffffffff816ecec3+AD4AXQ- handle+AF8-mm+AF8-fault+-0x2483/0x4640 mm/memory.c:3446
+AKAAoACgAKAAoABbADw-ffffffff8127eff6+AD4AXQ- +AF8AXw-do+AF8-page+AF8-fault+-0x376/0x960 arch/x86/mm/fault.c:1238
+AKAAoACgAKAAoABbADw-ffffffff8127f738+AD4AXQ- trace+AF8-do+AF8-page+AF8-fault+-0xe8/0x420 arch/x86/mm/fault.c:1331
+AKAAoACgAKAAoABbADw-ffffffff812705c4+AD4AXQ- do+AF8-async+AF8-page+AF8-fault+-0x14/0xd0 arch/x86/kernel/kvm.c:264
+AKAAoACgAKAAoABbADw-ffffffff86338f78+AD4AXQ- async+AF8-page+AF8-fault+-0x28/0x30 arch/x86/entry/entry+AF8-64.S:986
+AKAAoACgAKAAoABbADw-ffffffff86336c36+AD4AXQ- entry+AF8-SYSCALL+AF8-64+AF8-fastpath+-0x16/0x7a
+AKAAoACgAKA-arch/x86/entry/entry+AF8-64.S:185
+AKAAoACgAKA----+AFs- end trace dae21e0f85f1f98c +AF0----

Cc: Ross Zwisler +ADw-ross.zwisler+AEA-linux.intel.com+AD4-
Fixes: 5a023cdba50c (+ACI-block: enable dax for raw block devices+ACI-)
Reported-by: Dmitry Vyukov +ADw-dvyukov+AEA-google.com+AD4-
Reported-by: Kirill A. Shutemov +ADw-kirill+AEA-shutemov.name+AD4-
Suggested-by: Jan Kara +ADw-jack+AEA-suse.cz+AD4-
Reviewed-by: Jan Kara +ADw-jack+AEA-suse.cz+AD4-
Suggested-by: Matthew Wilcox +ADw-willy+AEA-linux.intel.com+AD4-
Signed-off-by: Dan Williams +ADw-dan.j.williams+AEA-intel.com+AD4-
---
+AKA-include/linux/fs.h +AHwAoACgAKAAoA-2 +--
+AKA-1 file changed, 1 insertion(+-), 1 deletion(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1a2046275cdf..b10002d4a5f5 100644
--- a/include/linux/fs.h
+-+-+- b/include/linux/fs.h
+AEAAQA- -2907,7 +-2907,7 +AEAAQA- extern void replace+AF8-mount+AF8-options(struct super+AF8-block +ACo-sb, char +ACo-options)+ADs-
+AKA-
+AKA-static inline bool io+AF8-is+AF8-direct(struct file +ACo-filp)
+AKAAew-
-	return (filp-+AD4-f+AF8-flags +ACY- O+AF8-DIRECT) +AHwAfA- IS+AF8-DAX(file+AF8-inode(filp))+ADs-
+-	return (filp-+AD4-f+AF8-flags +ACY- O+AF8-DIRECT) +AHwAfA- IS+AF8-DAX(filp-+AD4-f+AF8-mapping-+AD4-host)+ADs-
+AKAAfQ-
+AKA-
+AKA-static inline int iocb+AF8-flags(struct file +ACo-file)