linux-kernel - Re: [PATCH 00/11] Add compression support to pstore

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Date:	Mon, 5 Aug 2013 09:41:16 -0700
From:	Tony Luck <tony.luck@...il.com>
To:	Aruna Balakrishnaiah <aruna@...ux.vnet.ibm.com>,
	"linuxppc-dev@...abs.org" <linuxppc-dev@...abs.org>,
	"paulus@...ba.org" <paulus@...ba.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"benh@...nel.crashing.org" <benh@...nel.crashing.org>,
	"keescook@...omium.org" <keescook@...omium.org>
Subject: Re: [PATCH 00/11] Add compression support to pstore

One more experiment - removed previous hack that disabled compression.
Added a new hack to skip decompression.

System died cleanly when I forced a panic.
On reboot I found 3 files in pstore:
-r--r--r--   1 root root 3972 Aug  5 09:24 dmesg-erst-5908671953186586625
-r--r--r--   1 root root 2565 Aug  5 09:24 dmesg-erst-5908671953186586626
-r--r--r--   1 root root 4067 Aug  5 09:24 dmesg-erst-5908671953186586627

Using  "openssl zlib -d" to decompress then ends up with some garbage
at the end of the decompressed file - some text that should be there is
missing.  E.g. the tail of decompressed version of *625 ends with:

<4>Call Trace:
<4> [<ffffffff815f85f4>] dump_stack+0x45/0x56
<4> [<ffffffff815f41ca>] panic+0xc2/0x1cb
<4> [<ffffffff815f4327>] ? printk+0x54/0x56
<4> [<ffffffff811cfe45>] aegl+0x25/0x30
<4> [<ffffffff811c719d>] proc_reg_write+0x3d/0x80
<4> [<ffffffff81165945>] vfs_write+0xc5/0x1e0
<4> [<ffffffff81165e32>] SyS_write+0x52/0xa0
<4> [<ffffffff81606882>] system_call_fastpath+0x16/0x1b
 )c10^@^@^@^@^@^@^@^@^@

But my serial console logged this:

Call Trace:
 [<ffffffff815f85f4>] dump_stack+0x45/0x56
 [<ffffffff815f41ca>] panic+0xc2/0x1cb
 [<ffffffff815f4327>] ? printk+0x54/0x56
 [<ffffffff811cfe45>] aegl+0x25/0x30
 [<ffffffff811c719d>] proc_reg_write+0x3d/0x80
 [<ffffffff81165945>] vfs_write+0xc5/0x1e0
 [<ffffffff81165e32>] SyS_write+0x52/0xa0
 [<ffffffff81606882>] system_call_fastpath+0x16/0x1b
------------[ cut here ]------------
WARNING: CPU: 18 PID: 381 at arch/x86/kernel/smp.c:124
native_smp_send_reschedule+0x5b/0x60()
Modules linked in:
CPU: 18 PID: 381 Comm: kworker/18:1 Not tainted 3.11.0-rc3-11-ge41db9e #6

-Tony
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