linux-kernel - Re: [PATCH] mm: prevent RCU stalls in kswapd by adding cond

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Message-ID: <aJdkmCP41RhNC9FH@casper.infradead.org>
Date: Sat, 9 Aug 2025 16:09:12 +0100
From: Matthew Wilcox <willy@...radead.org>
To: "Subrata Nath (Nokia)" <subrata.nath@...ia.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm: prevent RCU stalls in kswapd by adding cond_resched()

On Sat, Aug 09, 2025 at 11:59:16AM +0000, Subrata Nath (Nokia) wrote:
> Fix this by adding cond_resched() after all spinlock release points
> in page_vma_mapped_walk() and in the main loop of shrink_zones().
> These calls, placed outside spinlock-held sections, allow voluntary
> scheduling and ensure timely quiescent state reporting, avoiding
> prolonged RCU stalls.

No.  We're removing cond_resched().  See
https://lore.kernel.org/linux-mm/87cyyfxd4k.ffs@tglx/
and many many other emails over the past few years.