The patch titled
Subject: mm/page_alloc: clear pages in alloc_contig_pages() with init_on_alloc=1 or __GFP_ZERO
has been removed from the -mm tree. Its filename was
mm-page_alloc-clear-pages-in-alloc_contig_pages-with-init_on_alloc=1-or-__gfp_zero.patch
This patch was dropped because it is obsolete
------------------------------------------------------
From: David Hildenbrand <david@xxxxxxxxxx>
Subject: mm/page_alloc: clear pages in alloc_contig_pages() with init_on_alloc=1 or __GFP_ZERO
commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and
init_on_free=1 boot options") resulted with init_on_alloc=1 in all pages
leaving the buddy via alloc_pages() and friends to be
initialized/cleared/zeroed on allocation.
However, the same logic is currently not applied to alloc_contig_pages():
allocated pages leaving the buddy aren't cleared with init_on_alloc=1 and
init_on_free=0. Let's also properly clear pages on that allocation path
and add support for __GFP_ZERO.
With this change, we will see double clearing of pages in some cases. One
example are gigantic pages (either allocated via CMA, or allocated
dynamically via alloc_contig_pages()) - which is the right thing to do
(and to be optimized outside of the buddy in the callers) as discussed in
https://lkml.kernel.org/r/20201019182853.7467-1-gpiccoli@xxxxxxxxxxxxx
This change implies that with init_on_alloc=1
- All CMA allocations will be cleared
- Gigantic pages allocated via alloc_contig_pages() will be cleared
- virtio-mem memory to be unplugged will be cleared. While this is
suboptimal, it's similar to memory balloon drivers handling, where
all pages to be inflated will get cleared as well.
__GFP_ZERO is not used yet. It's intended to be used in
https://lkml.kernel.org/r/20201029162718.29910-1-david@xxxxxxxxxx and I
can move that change into a separate patch if desired.
Link: https://lkml.kernel.org/r/20201110193240.25401-1-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-clear-pages-in-alloc_contig_pages-with-init_on_alloc=1-or-__gfp_zero
+++ a/mm/page_alloc.c
@@ -8477,6 +8477,19 @@ static int __alloc_contig_migrate_range(
return 0;
}
+static void __alloc_contig_clear_range(unsigned long start_pfn,
+ unsigned long end_pfn)
+{
+ unsigned long pfn;
+
+ for (pfn = start_pfn; pfn < end_pfn; pfn += MAX_ORDER_NR_PAGES) {
+ cond_resched();
+ kernel_init_free_pages(pfn_to_page(pfn),
+ min_t(unsigned long, end_pfn - pfn,
+ MAX_ORDER_NR_PAGES));
+ }
+}
+
/**
* alloc_contig_range() -- tries to allocate given range of pages
* @start: start PFN to allocate
@@ -8485,7 +8498,8 @@ static int __alloc_contig_migrate_range(
* #MIGRATE_MOVABLE or #MIGRATE_CMA). All pageblocks
* in range must have the same migratetype and it must
* be either of the two.
- * @gfp_mask: GFP mask to use during compaction
+ * @gfp_mask: GFP mask to use during compaction. __GFP_ZERO clears allocated
+ * pages.
*
* The PFN range does not have to be pageblock or MAX_ORDER_NR_PAGES
* aligned. The PFN range must belong to a single zone.
@@ -8512,7 +8526,7 @@ int alloc_contig_range(unsigned long sta
.mode = MIGRATE_SYNC,
.ignore_skip_hint = true,
.no_set_skip_hint = true,
- .gfp_mask = current_gfp_context(gfp_mask),
+ .gfp_mask = current_gfp_context(gfp_mask & ~__GFP_ZERO),
.alloc_contig = true,
};
INIT_LIST_HEAD(&cc.migratepages);
@@ -8626,6 +8640,9 @@ int alloc_contig_range(unsigned long sta
if (end != outer_end)
free_contig_range(end, outer_end - end);
+ if (!want_init_on_free() && want_init_on_alloc(gfp_mask))
+ __alloc_contig_clear_range(start, end);
+
done:
undo_isolate_page_range(pfn_max_align_down(start),
pfn_max_align_up(end), migratetype);
@@ -8679,7 +8696,8 @@ static bool zone_spans_last_pfn(const st
/**
* alloc_contig_pages() -- tries to find and allocate contiguous range of pages
* @nr_pages: Number of contiguous pages to allocate
- * @gfp_mask: GFP mask to limit search and used during compaction
+ * @gfp_mask: GFP mask to limit search and used during compaction. __GFP_ZERO
+ * clears allocated pages.
* @nid: Target node
* @nodemask: Mask for other possible nodes
*
_
Patches currently in -mm which might be from david@xxxxxxxxxx are
mm-page_alloc-clear-all-pages-in-post_alloc_hook-with-init_on_alloc=1.patch
