linux-kernel - Re: [BUG][powerpc] OOPs: Kernel access of bad area during zram swap write

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Message-ID: <bcec125a551e086911f82cef7bd632fd@linux.ibm.com>
Date: Mon, 28 Apr 2025 10:39:16 +0530
From: Misbah Anjum N <misanjum@...ux.ibm.com>
To: Ritesh Harjani <riteshh@...ux.ibm.com>
Cc: christophe.leroy@...roup.eu, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org, maddy@...ux.ibm.com,
        mpe@...erman.id.au, naveen@...nel.org, npiggin@...il.com
Subject: Re: [BUG][powerpc] OOPs: Kernel access of bad area during zram swap
 write - kswapd0 crash

On 2025-04-21 09:19, Ritesh Harjani wrote:

> Looks like the issue is happening on 6.15-rc2. Did git bisect revealed 
> a
> faulty commit?
> 
> Looks like zsmalloc new object mapping API being called, which was
> merged in rc1?  But let's first confirm from git bisect, unless someone
> from linux-mm who knows zsmalloc subsystem better and can point on what
> could be going wrong here.
> 
> -ritesh

Hi,

Regarding the issue, I am currently running tests by removing the 
suspected faulty commit. Unfortunately, git bisect is not feasible in 
this case because recreating the bug requires running the avocado bucket 
for approximately two days. Hence, I am resetting the kernel to the 
commit prior to: 44f76413496ec343da0d8292ceecdcabe3e6ec16 and manually 
running the bucket to come to conclusions.

The commit in question: 44f76413496ec343da0d8292ceecdcabe3e6ec16 
introduces zsmalloc - new object mapping API
More information: 
https://github.com/torvalds/linux/commit/44f76413496ec343da0d8292ceecdcabe3e6ec16

I will update the upstream bug report with this information after 
performing the tests.
Thank you,
Misbah Anjum N