Re: [PATCH] xen/page_alloc: Don't hold the heap_lock when clearing PGC_need_scrub

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.04.2021 21:30, Julien Grall wrote:
> From: Julien Grall <jgrall@xxxxxxxxxx>
> 
> Currently, the heap_lock is held when clearing PGC_need_scrub in
> alloc_heap_pages(). However, this is unnecessary because the only caller
> (mark_page_offline()) that can concurrently modify the count_info is
> using cmpxchg() in a loop.
> 
> Therefore, rework the code to avoid holding the heap_lock and use
> test_and_clear_bit() instead.
> 
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>