linux-kernel - [PATCH] mm/vmalloc: Don't unconditonally use __GFP

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Message-Id: <20170816220705.31374-1-labbott@redhat.com>
Date:   Wed, 16 Aug 2017 15:07:05 -0700
From:   Laura Abbott <labbott@...hat.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Laura Abbott <labbott@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mm/vmalloc: Don't unconditonally use __GFP_HIGHMEM

Commit 19809c2da28a ("mm, vmalloc: use __GFP_HIGHMEM implicitly")
added use of __GFP_HIGHMEM for allocations. vmalloc_32 may use
GFP_DMA/GFP_DMA32 which does not play nice with __GFP_HIGHMEM
and will drigger a BUG in gfp_zone. Only add __GFP_HIGHMEM if
we aren't using GFP_DMA/GFP_DMA32.

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1482249
Fixes: 19809c2da28a ("mm, vmalloc: use __GFP_HIGHMEM implicitly")
Signed-off-by: Laura Abbott <labbott@...hat.com>
---
 mm/vmalloc.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 8698c1c86c4d..a47e3894c775 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1671,7 +1671,10 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 	struct page **pages;
 	unsigned int nr_pages, array_size, i;
 	const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
-	const gfp_t alloc_mask = gfp_mask | __GFP_HIGHMEM | __GFP_NOWARN;
+	const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
+	const gfp_t highmem_mask = (gfp_mask & (GFP_DMA | GFP_DMA32)) ?
+					0 :
+					__GFP_HIGHMEM;
 
 	nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
 	array_size = (nr_pages * sizeof(struct page *));
@@ -1679,7 +1682,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 	area->nr_pages = nr_pages;
 	/* Please note that the recursion is strictly bounded. */
 	if (array_size > PAGE_SIZE) {
-		pages = __vmalloc_node(array_size, 1, nested_gfp|__GFP_HIGHMEM,
+		pages = __vmalloc_node(array_size, 1, nested_gfp|highmem_mask,
 				PAGE_KERNEL, node, area->caller);
 	} else {
 		pages = kmalloc_node(array_size, nested_gfp, node);
@@ -1700,9 +1703,9 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 		}
 
 		if (node == NUMA_NO_NODE)
-			page = alloc_page(alloc_mask);
+			page = alloc_page(alloc_mask|highmem_mask);
 		else
-			page = alloc_pages_node(node, alloc_mask, 0);
+			page = alloc_pages_node(node, alloc_mask|highmem_mask, 0);
 
 		if (unlikely(!page)) {
 			/* Successfully allocated i pages, free them in __vunmap() */
@@ -1710,7 +1713,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 			goto fail;
 		}
 		area->pages[i] = page;
-		if (gfpflags_allow_blocking(gfp_mask))
+		if (gfpflags_allow_blocking(gfp_mask|highmem_mask))
 			cond_resched();
 	}
 
-- 
2.13.0