linux-kernel - Re: [6.2][regression] after commit 947a629988f191807d2d22ba63ae18259bb645c5 btrfs volume periodical forced switch to readonly after a lot of disk writes

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Date:   Tue, 27 Dec 2022 13:13:52 +0800
From:   Qu Wenruo <quwenruo.btrfs@....com>
To:     Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
Cc:     wqu@...e.com, dsterba@...e.com,
        Btrfs BTRFS <linux-btrfs@...r.kernel.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>
Subject: Re: [6.2][regression] after commit
 947a629988f191807d2d22ba63ae18259bb645c5 btrfs volume periodical forced
 switch to readonly after a lot of disk writes

On 2022/12/27 09:35, Mikhail Gavrilov wrote:
> On Tue, Dec 27, 2022 at 5:18 AM Qu Wenruo <quwenruo.btrfs@....com> wrote:
>>
>> My bad, missing a ")" in the WARN_ON() line.
>>
>> Fixed with v3 patch.
>>
> 
> New kernel logs are ready.
> 

The result doesn't make sense...

A lot of read_block_for_search() and btrfs_read_node_slot() are 
triggering the warning.

But inside both functions, we have just set the numbers before the call:

In read_block_for_search() we got:

         check.has_first_key = true;
         check.level = parent_level - 1;
         check.transid = gen;
         check.owner_root = root->root_key.objectid;

Thus at least check.has_first_key is always true, and the WARN_ON() 
should never get triggered.
The same applies to btrfs_read_node_slot().

It looks like something involved in memory barrier.

Anyway, the latest debug patch has extra mb to be sure.

And despite the possible fix, could you provide extra info of your 
build? Include:

- Hardware (mostly CPU and RAM spec)
- Toolchain used to compile the kernel (include compiler and its
   version)
- Kernel config

Thanks,
Qu
View attachment "0001-btrfs-add-extra-debug-for-level-mismatch.patch" of type "text/x-patch" (4360 bytes)