From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
To: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
Dan Williams <dan.j.williams@intel.com>,
Laurent Dufour <ldufour@linux.vnet.ibm.com>
Subject: Re: [PATCH 0/4 v2] BDI lifetime fix
Date: Mon, 06 Feb 2017 13:26:53 -0200 [thread overview]
Message-ID: <1790906.I1Z25HtRf4@morokweng> (raw)
In-Reply-To: <2851869.q2N89k4IqL@morokweng>
Am Montag, 6. Februar 2017, 12:48:42 BRST schrieb Thiago Jung Bauermann:
> 216 static inline void wb_get(struct bdi_writeback *wb)
> 217 {
> 218 if (wb != &wb->bdi->wb)
> 219 percpu_ref_get(&wb->refcnt);
> 220 }
>
> So it looks like wb->bdi is NULL.
Sorry, looking a little deeper, it's actually wb which is NULL:
./include/linux/backing-dev.h:
371 return inode->i_wb;
0xc00000000037999c <+76>: ld r31,256(r29)
./include/linux/backing-dev-defs.h:
218 if (wb != &wb->bdi->wb)
0xc0000000003799a0 <+80>: ld r9,0(r31)
0xc0000000003799a4 <+84>: addi r9,r9,88
0xc0000000003799a8 <+88>: cmpld cr7,r31,r9
0xc0000000003799ac <+92>: beq cr7,0xc0000000003799e0
<locked_inode_to_wb_and_lock_list+144>
We can see above that inode->i_wb is in r31, and the machine crashed at
0xc0000000003799a0 so it was trying to dereference wb and crashed.
r31 is NULL in the crash information.
--
Thiago Jung Bauermann
IBM Linux Technology Center
next prev parent reply other threads:[~2017-02-06 15:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-31 12:54 [PATCH 0/4 v2] BDI lifetime fix Jan Kara
2017-01-31 12:54 ` [PATCH 1/4] block: Unhash block device inodes on gendisk destruction Jan Kara
2017-02-01 9:48 ` Christoph Hellwig
2017-01-31 12:54 ` [PATCH 2/4] block: Use pointer to backing_dev_info from request_queue Jan Kara
2017-02-01 9:48 ` Christoph Hellwig
2017-01-31 12:54 ` [PATCH 3/4] block: Dynamically allocate and refcount backing_dev_info Jan Kara
2017-02-01 9:50 ` Christoph Hellwig
2017-02-01 12:22 ` Jan Kara
2017-02-01 22:45 ` Jens Axboe
2017-02-02 13:32 ` Jan Kara
2017-01-31 12:54 ` [PATCH 4/4] block: Make blk_get_backing_dev_info() safe without open bdev Jan Kara
2017-02-01 9:53 ` Christoph Hellwig
2017-02-01 12:28 ` Jan Kara
2017-02-01 12:52 ` Christoph Hellwig
2017-02-01 19:25 ` Dan Williams
2017-02-06 14:48 ` [PATCH 0/4 v2] BDI lifetime fix Thiago Jung Bauermann
2017-02-06 15:26 ` Thiago Jung Bauermann [this message]
2017-02-07 12:33 ` Jan Kara
2017-02-07 17:21 ` Tejun Heo
2017-02-08 7:51 ` Jan Kara
2017-02-08 10:23 ` Jan Kara
2017-02-08 16:00 ` Dan Williams
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