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

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Date:	Fri, 2 Aug 2013 14:39:55 -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>
Cc:	"jkenisto@...ux.vnet.ibm.com" <jkenisto@...ux.vnet.ibm.com>,
	"mahesh@...ux.vnet.ibm.com" <mahesh@...ux.vnet.ibm.com>,
	"cbouatmailru@...il.com" <cbouatmailru@...il.com>,
	"anton@...ba.org" <anton@...ba.org>,
	"ccross@...roid.com" <ccross@...roid.com>
Subject: Re: [PATCH 00/11] Add compression support to pstore

On Thu, Aug 1, 2013 at 4:42 PM, Luck, Tony <tony.luck@...el.com> wrote:
> when I rebuilt a plain 3.11-rc3 it didn't log anything via pstore either :-(

Well this turned out to be operator error on my part. 3.11-rc3 does in fact
log errors to pstore and allows them to be retrieved and cleared.

So then I start testing with your 11 patches in place.

First boot was fine - ERST had no records, and pstore mounted OK
(and showed no files).

Then I panic'd the machine and rebooted.  The boot hung when some
rc script printed"

Mounting other filesystems:

I guess something went wrong when pstore found a non-empty ERST.

I added some debug traces and booted again.  This time the boot succeeded
but I saw a GP fault reported from pstore_mkfile(). Possibly in this code:

        spin_lock_irqsave(&allpstore_lock, flags);
        list_for_each_entry(pos, &allpstore, list) {
                if (pos->type == type &&
                    pos->id == id &&
                    pos->psi == psi) {
                        rc = -EEXIST;
                        break;
                }
        }
        spin_unlock_irqrestore(&allpstore_lock, flags);

My other tracing showed that we'd already found two compressed entries in
ERST and were working on a third when this error happened (implying that
my hang had been a panic that failed to print anything to console)

I've attached one of the compressed files that v3.11-rc3 shows in pstore
now.  The "openssl zlib -d" trick you mentioned back in June mostly works
to decode ... but it seems to dump some trailing garbage at the end of
the file.

-Tony

Download attachment "unknown-erst-5907623178007478273" of type "application/octet-stream" (4375 bytes)