Re: [regression v6.5-rc1] PCI: comm "swapper/0" leaking memory

From: Kalle Valo <kvalo@kernel.org>
To: Ross Lagerwall <ross.lagerwall@cloud.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
	 linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	 ath11k@lists.infradead.org, regressions@lists.linux.dev
Subject: Re: [regression v6.5-rc1] PCI: comm "swapper/0" leaking memory
Date: Wed, 06 Sep 2023 11:40:52 +0300	[thread overview]
Message-ID: <87o7ifelt7.fsf@kernel.org> (raw)
In-Reply-To: <CAG7k0Epk6KJvoDJKVc86sc_ems3DTbKvPLouBzOoVvn1tZwQ=w@mail.gmail.com> (Ross Lagerwall's message of "Tue, 5 Sep 2023 17:28:38 +0100")

Ross Lagerwall <ross.lagerwall@cloud.com> writes:

> On Wed, Aug 30, 2023 at 10:21 AM Kalle Valo <kvalo@kernel.org> wrote:
>
>>
>> I noticed that starting from v6.5-rc1 my ath11k tests reported several
>> memory leaks from swapper/0:
>>
>> unreferenced object 0xffff88810a02b7a8 (size 96):
>>   comm "swapper/0", pid 1, jiffies 4294671838 (age 98.120s)
>>   hex dump (first 32 bytes):
>>     80 b8 02 0a 81 88 ff ff b8 72 07 00 00 c9 ff ff  .........r......
>>     c8 b7 02 0a 81 88 ff ff 00 00 00 00 00 00 00 00  ................
>>   backtrace:
>> unreferenced object 0xffff88810a02b880 (size 96):
>>   comm "swapper/0", pid 1, jiffies 4294671838 (age 98.120s)
>>   hex dump (first 32 bytes):
>>     58 b9 02 0a 81 88 ff ff a8 b7 02 0a 81 88 ff ff  X...............
>>     a0 b8 02 0a 81 88 ff ff 00 00 00 00 00 00 00 00  ................
>>   backtrace:
>> unreferenced object 0xffff88810a02b958 (size 96):
>>   comm "swapper/0", pid 1, jiffies 4294671838 (age 98.120s)
>>   hex dump (first 32 bytes):
>>     30 ba 02 0a 81 88 ff ff 80 b8 02 0a 81 88 ff ff  0...............
>>     78 b9 02 0a 81 88 ff ff 00 00 00 00 00 00 00 00  x...............
>>   backtrace:
>> unreferenced object 0xffff88810a02ba30 (size 96):
>>   comm "swapper/0", pid 1, jiffies 4294671838 (age 98.120s)
>>   hex dump (first 32 bytes):
>>     08 bb 02 0a 81 88 ff ff 58 b9 02 0a 81 88 ff ff  ........X.......
>>     50 ba 02 0a 81 88 ff ff 00 00 00 00 00 00 00 00  P...............
>>   backtrace:
>> unreferenced object 0xffff88810a02bb08 (size 96):
>>   comm "swapper/0", pid 1, jiffies 4294671838 (age 98.120s)
>>   hex dump (first 32 bytes):
>>     e0 bb 02 0a 81 88 ff ff 30 ba 02 0a 81 88 ff ff  ........0.......
>>     28 bb 02 0a 81 88 ff ff 00 00 00 00 00 00 00 00  (...............
>>   backtrace:
>>
>> I can easily reproduce this by doing a simple insmod and rmmod of ath11k
>> and it's dependencies (mac80211, MHI etc). I can reliability reproduce
>> the leaks but I only see them once after a boot, I need to reboot the
>> host to see the leaks again. v6.4 has no leaks.
>>
>> I did a bisect and found the commit below. I verified reverting the
>> commit makes the leaks go away.
>>
>> commit e54223275ba1bc6f704a6bab015fcd2ae4f72572
>> Author:     Ross Lagerwall <ross.lagerwall@citrix.com>
>> AuthorDate: Thu May 25 16:32:48 2023 +0100
>> Commit:     Bjorn Helgaas <bhelgaas@google.com>
>> CommitDate: Fri Jun 9 15:06:16 2023 -0500
>>
>>     PCI: Release resource invalidated by coalescing
>
> Hi Kalle,
>
> I can't reproduce the leak by loading/unloading the ath11k module. I suspect
> that the leak is always there when PCI resources are coalesced but
> kmemleak doesn't notice until ath11k is loaded.
>
> Can you please try the following to confirm it fixes it?

I run various tests with your patch and I don't see leaks anymore. I
also veried that without your patch I see the leak immediately.

Thanks for fixing this so quickly, it would good to have this fix in
v6.6 if possible.

Tested-by: Kalle Valo <kvalo@kernel.org>

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