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

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Date:   Fri, 21 May 2021 00:43:46 -0700
From:   Alexey Makhalov <amakhalov@...are.com>
To:     "Theodore Y. Ts'o" <tytso@....edu>
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

Hi Ted,

Good point! This paragraph can be just dropped as the next one
describes the issue with superblock re-read. Will send v2 shortly.

Thanks,
—Alexey

> On May 20, 2021, at 9:43 PM, Theodore Y. Ts'o <tytso@....edu> wrote:
> 
> 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


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