linux-kernel - Re: [PATCH 09/11] mm/page_alloc: Avoid conflating IRQs disabled with zone->lock

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Date:   Thu, 15 Apr 2021 15:11:06 +0100
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Linux-MM <linux-mm@...ck.org>,
        Linux-RT-Users <linux-rt-users@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Chuck Lever <chuck.lever@...cle.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Michal Hocko <mhocko@...nel.org>
Subject: Re: [PATCH 09/11] mm/page_alloc: Avoid conflating IRQs disabled with
 zone->lock

On Thu, Apr 15, 2021 at 02:25:36PM +0200, Vlastimil Babka wrote:
> > @@ -3294,6 +3295,7 @@ void free_unref_page_list(struct list_head *list)
> >  	struct page *page, *next;
> >  	unsigned long flags, pfn;
> >  	int batch_count = 0;
> > +	int migratetype;
> >  
> >  	/* Prepare pages for freeing */
> >  	list_for_each_entry_safe(page, next, list, lru) {
> > @@ -3301,15 +3303,28 @@ void free_unref_page_list(struct list_head *list)
> >  		if (!free_unref_page_prepare(page, pfn))
> >  			list_del(&page->lru);
> >  		set_page_private(page, pfn);
> 
> Should probably move this below so we don't set private for pages that then go
> through free_one_page()? Doesn't seem to be a bug, just unneccessary.
> 

Sure.

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1d87ca364680..a9c1282d9c7b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3293,7 +3293,6 @@ void free_unref_page_list(struct list_head *list)
 		pfn = page_to_pfn(page);
 		if (!free_unref_page_prepare(page, pfn))
 			list_del(&page->lru);
-		set_page_private(page, pfn);
 
 		/*
 		 * Free isolated pages directly to the allocator, see
@@ -3307,6 +3306,8 @@ void free_unref_page_list(struct list_head *list)
 				list_del(&page->lru);
 			}
 		}
+
+		set_page_private(page, pfn);
 	}
 
 	local_lock_irqsave(&pagesets.lock, flags);

-- 
Mel Gorman
SUSE Labs