From: Peter Zijlstra <peterz@infradead.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
linux-mm@kvack.org, Alexander Duyck <alexander.duyck@gmail.com>,
Alex Shi <alex.shi@linux.alibaba.com>,
Hugh Dickins <hughd@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH] memcg: Optimise relock_page_lruvec functions
Date: Mon, 25 Oct 2021 13:16:46 +0200 [thread overview]
Message-ID: <YXaSHlqcBqLPnJ/0@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <c0335508-7174-ae03-ad90-82a65d35b6d6@suse.cz>
On Mon, Oct 25, 2021 at 12:44:05PM +0200, Vlastimil Babka wrote:
> On 10/19/21 14:50, Matthew Wilcox (Oracle) wrote:
> > Leave interrupts disabled when we change which lru lock is held.
> >
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>
> Assuming lockdep is fine with e.g.:
>
> spin_lock_irqsave(A);
> spin_unlock(A);
> spin_lock(B);
> spin_unlock_irqrestore(B);
>
> (with A and B of same class).
It's unconditionally okay with that pattern. As far as lockdep
is concerned there really is no differences vs:
local_irq_save()
spin_lock(a)
spin_unlock(a)
spin_lock(b)
spin_unlock(b)
local_irq_restore()
It's the RT locking primitives that care about the difference :-)
prev parent reply other threads:[~2021-10-25 11:16 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-19 12:50 [PATCH] memcg: Optimise relock_page_lruvec functions Matthew Wilcox (Oracle)
2021-10-25 10:44 ` Vlastimil Babka
2021-10-25 11:16 ` Peter Zijlstra [this message]
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