linux-kernel - [PATCH 1/7] mm/page_alloc: Move gfp_allowed_mask enforcement to prepare_alloc

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Date:   Fri, 12 Mar 2021 15:43:25 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Chuck Lever <chuck.lever@...cle.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Matthew Wilcox <willy@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-Net <netdev@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        Linux-NFS <linux-nfs@...r.kernel.org>,
        Mel Gorman <mgorman@...hsingularity.net>
Subject: [PATCH 1/7] mm/page_alloc: Move gfp_allowed_mask enforcement to prepare_alloc_pages

__alloc_pages updates GFP flags to enforce what flags are allowed
during a global context such as booting or suspend. This patch moves the
enforcement from __alloc_pages to prepare_alloc_pages so the code can be
shared between the single page allocator and a new bulk page allocator.

When moving, it is obvious that __alloc_pages() and __alloc_pages
use different names for the same variable. This is an unnecessary
complication so rename gfp_mask to gfp in prepare_alloc_pages() so the
name is consistent.

No functional change.

Signed-off-by: Mel Gorman <mgorman@...hsingularity.net>
---
 mm/page_alloc.c | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 00b67c47ad87..f0c1d74ead6f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4914,15 +4914,18 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	return page;
 }
 
-static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
+static inline bool prepare_alloc_pages(gfp_t gfp, unsigned int order,
 		int preferred_nid, nodemask_t *nodemask,
 		struct alloc_context *ac, gfp_t *alloc_gfp,
 		unsigned int *alloc_flags)
 {
-	ac->highest_zoneidx = gfp_zone(gfp_mask);
-	ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
+	gfp &= gfp_allowed_mask;
+	*alloc_gfp = gfp;
+
+	ac->highest_zoneidx = gfp_zone(gfp);
+	ac->zonelist = node_zonelist(preferred_nid, gfp);
 	ac->nodemask = nodemask;
-	ac->migratetype = gfp_migratetype(gfp_mask);
+	ac->migratetype = gfp_migratetype(gfp);
 
 	if (cpusets_enabled()) {
 		*alloc_gfp |= __GFP_HARDWALL;
@@ -4936,18 +4939,18 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 			*alloc_flags |= ALLOC_CPUSET;
 	}
 
-	fs_reclaim_acquire(gfp_mask);
-	fs_reclaim_release(gfp_mask);
+	fs_reclaim_acquire(gfp);
+	fs_reclaim_release(gfp);
 
-	might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
+	might_sleep_if(gfp & __GFP_DIRECT_RECLAIM);
 
-	if (should_fail_alloc_page(gfp_mask, order))
+	if (should_fail_alloc_page(gfp, order))
 		return false;
 
-	*alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags);
+	*alloc_flags = current_alloc_flags(gfp, *alloc_flags);
 
 	/* Dirty zone balancing only done in the fast path */
-	ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE);
+	ac->spread_dirty_pages = (gfp & __GFP_WRITE);
 
 	/*
 	 * The preferred zone is used for statistics but crucially it is
@@ -4980,8 +4983,6 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid,
 		return NULL;
 	}
 
-	gfp &= gfp_allowed_mask;
-	alloc_gfp = gfp;
 	if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac,
 			&alloc_gfp, &alloc_flags))
 		return NULL;
-- 
2.26.2