linux-kernel - Re: [PATCH] mbcache: Avoid nesting of cache->c_list

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Message-Id: <166450797715.256913.1802115613587243672.b4-ty@mit.edu>
Date:   Thu, 29 Sep 2022 23:19:36 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Jan Kara <jack@...e.cz>
Cc:     "Theodore Ts'o" <tytso@....edu>, linux-ext4@...r.kernel.org,
        bigeasy@...utronix.de, LKML <linux-kernel@...r.kernel.org>,
        efault@....de
Subject: Re: [PATCH] mbcache: Avoid nesting of cache->c_list_lock under bit locks

On Thu, 8 Sep 2022 11:10:32 +0200, Jan Kara wrote:
> Commit 307af6c87937 ("mbcache: automatically delete entries from cache
> on freeing") started nesting cache->c_list_lock under the bit locks
> protecting hash buckets of the mbcache hash table in
> mb_cache_entry_create(). This causes problems for real-time kernels
> because there spinlocks are sleeping locks while bitlocks stay atomic.
> Luckily the nesting is easy to avoid by holding entry reference until
> the entry is added to the LRU list. This makes sure we cannot race with
> entry deletion.
> 
> [...]

Applied, thanks!

[1/1] mbcache: Avoid nesting of cache->c_list_lock under bit locks
      commit: 9cbf99ae41e3a051cc9ec738f2c436ec1725e0e8

Best regards,
-- 
Theodore Ts'o <tytso@....edu>