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Date: Tue, 26 Jan 2016 03:42:34 +0000
From: "Williams, Dan J" <dan.j.williams@...el.com>
To: "kirill@...temov.name" <kirill@...temov.name>,
"jack@...e.cz" <jack@...e.cz>
CC: "syzkaller@...glegroups.com" <syzkaller@...glegroups.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
"kcc@...gle.com" <kcc@...gle.com>,
"vbabka@...e.cz" <vbabka@...e.cz>,
"viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
"dvyukov@...gle.com" <dvyukov@...gle.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"gthelen@...gle.com" <gthelen@...gle.com>,
"willy@...ux.intel.com" <willy@...ux.intel.com>,
"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
"mhocko@...e.com" <mhocko@...e.com>,
"jack@...e.com" <jack@...e.com>,
"glider@...gle.com" <glider@...gle.com>,
"sasha.levin@...cle.com" <sasha.levin@...cle.com>,
"Wilcox, Matthew R" <matthew.r.wilcox@...el.com>,
"j-nomura@...jp.nec.com" <j-nomura@...jp.nec.com>
Subject: Re: mm: WARNING in __delete_from_page_cache
On Mon, 2016-01-25 at 13:22 +0100, Jan Kara wrote:
[..]
> Thanks. Despite the huge list of recipients the author of the changes
> hasn't been CCed :) I've added Dan to CC since he wrote DAX support
> for
> block devices. It seems somehow the write didn't go through the DAX
> path
> but through the standard page cache write path. Ah, I see, only
> file->f_mapping->host has S_DAX set but io_is_direct() which decides
> whether DAX or pagecache path should be used for writes uses file-
> >f_inode
> which is something different for block devices...
Thanks, yes, the following silences the warning for me:
8<----- (git am --scissors)
Subject: fs, block: force direct-I/O for dax-enabled block devices
From: Dan Williams <dan.j.williams@...el.com>
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.
Otherwise, we confuse the DAX code that does not expect to find live
data in the page cache:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 7676 at mm/filemap.c:217
__delete_from_page_cache+0x9f6/0xb60()
Modules linked in:
CPU: 0 PID: 7676 Comm: a.out Not tainted 4.4.0+ #276
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
00000000ffffffff ffff88006d3f7738 ffffffff82999e2d 0000000000000000
ffff8800620a0000 ffffffff86473d20 ffff88006d3f7778 ffffffff81352089
ffffffff81658d36 ffffffff86473d20 00000000000000d9 ffffea0000009d60
Call Trace:
[< inline >] __dump_stack lib/dump_stack.c:15
[<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
[<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
[<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
[<ffffffff81658d36>] __delete_from_page_cache+0x9f6/0xb60 mm/filemap.c:217
[<ffffffff81658fb2>] delete_from_page_cache+0x112/0x200 mm/filemap.c:244
[<ffffffff818af369>] __dax_fault+0x859/0x1800 fs/dax.c:487
[<ffffffff8186f4f6>] blkdev_dax_fault+0x26/0x30 fs/block_dev.c:1730
[< inline >] wp_pfn_shared mm/memory.c:2208
[<ffffffff816e9145>] do_wp_page+0xc85/0x14f0 mm/memory.c:2307
[< inline >] handle_pte_fault mm/memory.c:3323
[< inline >] __handle_mm_fault mm/memory.c:3417
[<ffffffff816ecec3>] handle_mm_fault+0x2483/0x4640 mm/memory.c:3446
[<ffffffff8127eff6>] __do_page_fault+0x376/0x960 arch/x86/mm/fault.c:1238
[<ffffffff8127f738>] trace_do_page_fault+0xe8/0x420 arch/x86/mm/fault.c:1331
[<ffffffff812705c4>] do_async_page_fault+0x14/0xd0 arch/x86/kernel/kvm.c:264
[<ffffffff86338f78>] async_page_fault+0x28/0x30 arch/x86/entry/entry_64.S:986
[<ffffffff86336c36>] entry_SYSCALL_64_fastpath+0x16/0x7a
arch/x86/entry/entry_64.S:185
---[ end trace dae21e0f85f1f98c ]---
Cc: Matthew Wilcox <willy@...ux.intel.com>
Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>
Fixes: 5a023cdba50c ("block: enable dax for raw block devices")
Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Reported-by: Kirill A. Shutemov <kirill@...temov.name>
Suggested-by: Jan Kara <jack@...e.cz>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
fs/block_dev.c | 5 -----
include/linux/fs.h | 12 +++++++++++-
2 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 7b9cd49622b1..277008617b2d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -156,11 +156,6 @@ blkdev_get_block(struct inode *inode, sector_t iblock,
return 0;
}
-static struct inode *bdev_file_inode(struct file *file)
-{
- return file->f_mapping->host;
-}
-
static ssize_t
blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t offset)
{
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1a2046275cdf..a4c4314eed48 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1237,6 +1237,11 @@ static inline struct inode *file_inode(const struct file *f)
return f->f_inode;
}
+static inline struct inode *bdev_file_inode(struct file *file)
+{
+ return file->f_mapping->host;
+}
+
static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl)
{
return locks_lock_inode_wait(file_inode(filp), fl);
@@ -2907,7 +2912,12 @@ extern void replace_mount_options(struct super_block *sb, char *options);
static inline bool io_is_direct(struct file *filp)
{
- return (filp->f_flags & O_DIRECT) || IS_DAX(file_inode(filp));
+ struct inode *inode = file_inode(filp);
+
+ if (S_ISBLK(inode->i_mode))
+ inode = bdev_file_inode(filp);
+
+ return (filp->f_flags & O_DIRECT) || IS_DAX(inode);
}
static inline int iocb_flags(struct file *file)
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