linux-kernel - Re: ipc/mqueue: release spinlock before freeing node_cache in mqueue_evict

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Message-ID: <20250627163758.GV1880847@ZenIV>
Date: Fri, 27 Jun 2025 17:37:58 +0100
From: Al Viro <viro@...iv.linux.org.uk>
To: ritu pal <ritupal888@...il.com>
Cc: linux-kernel@...r.kernel.org, Christian Brauner <brauner@...nel.org>,
	NeilBrown <neil@...wn.name>, Chen Ni <nichen@...as.ac.cn>
Subject: Re: ipc/mqueue: release spinlock before freeing node_cache in
 mqueue_evict_inode()

On Fri, Jun 27, 2025 at 06:11:14PM +0530, ritu pal wrote:
> Hi,
> 
> Currently, mqueue_evict_inode() holds info->lock while freeing
> info->node_cache
> with kfree(). Although kfree() does not sleep, it may take a non-trivial
> amount
> of time, increasing the duration the spinlock is held and potentially
> impacting
> concurrency.

That spinlock is inside the inode in question; what exactly is going to be
on the other side of contention?  Note that none of the file methods
are going to run concurrent with that...