linux-ext4 - Re: [PATCH] ext4: fix memory leak in ext4_fill

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Message-ID: <YKc6fidMj95TZp2w@mit.edu>
Date:   Fri, 21 May 2021 00:43:42 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Alexey Makhalov <amakhalov@...are.com>
Cc:     linux-ext4@...r.kernel.org, stable@...r.kernel.org,
        Andreas Dilger <adilger.kernel@...ger.ca>
Subject: Re: [PATCH] ext4: fix memory leak in ext4_fill_super

On Wed, Apr 28, 2021 at 10:19:28PM +0000, Alexey Makhalov wrote:
> I've recently discovered that doing infinite loop of
>   systemctl start <ext4_on_lvm>.mount, and
>   systemctl stop <ext4_on_lvm>.mount
> linearly increases percpu allocator memory consumption.
> In several hours, it might lead to system instability by
> consuming most of the memory.
> 
> Bug is not reproducible when the ext4 filesystem is on
> physical partition, but it is persistent when ext4 is on
> logical volume.

Why is this the case?  It sounds like we're looking a buffer for each
mount where the block size is not 1k.  It shouldn't matter whether it
is a physical partition or not.

				- Ted