The patch titled
Subject: mm/cma: fix potential memory loss on cma_declare_contiguous_nid
has been added to the -mm mm-unstable branch. Its filename is
mm-cma-fix-potential-memory-loss-on-cma_declare_contiguous_nid.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-cma-fix-potential-memory-loss-on-cma_declare_contiguous_nid.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Levi Yun <ppbuk5246@xxxxxxxxx>
Subject: mm/cma: fix potential memory loss on cma_declare_contiguous_nid
Date: Wed, 18 Jan 2023 17:05:23 +0900
Suppose memblock_alloc_range_nid() with highmem_start succeeds when
cma_declare_contiguous_nid is called with !fixed on a 32-bit system with
PHYS_ADDR_T_64BIT enabled with memblock.bottom_up == false.
But the next trial to memblock_alloc_range_nid() to allocate in [SIZE_4G,
limits) nullifies former successfully allocated addr and it retries
memblock_alloc_ragne_nid().
In this situation, the first successfully allocated address area is lost.
Change the order of allocation (SIZE_4G, high_memory and base) and check
whether the allocated succeeded to prevent potential memory loss.
Link: https://lkml.kernel.org/r/20230118080523.44522-1-ppbuk5246@xxxxxxxxx
Signed-off-by: Levi Yun <ppbuk5246@xxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/cma.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
--- a/mm/cma.c~mm-cma-fix-potential-memory-loss-on-cma_declare_contiguous_nid
+++ a/mm/cma.c
@@ -331,18 +331,6 @@ int __init cma_declare_contiguous_nid(ph
phys_addr_t addr = 0;
/*
- * All pages in the reserved area must come from the same zone.
- * If the requested region crosses the low/high memory boundary,
- * try allocating from high memory first and fall back to low
- * memory in case of failure.
- */
- if (base < highmem_start && limit > highmem_start) {
- addr = memblock_alloc_range_nid(size, alignment,
- highmem_start, limit, nid, true);
- limit = highmem_start;
- }
-
- /*
* If there is enough memory, try a bottom-up allocation first.
* It will place the new cma area close to the start of the node
* and guarantee that the compaction is moving pages out of the
@@ -359,6 +347,18 @@ int __init cma_declare_contiguous_nid(ph
}
#endif
+ /*
+ * All pages in the reserved area must come from the same zone.
+ * If the requested region crosses the low/high memory boundary,
+ * try allocating from high memory first and fall back to low
+ * memory in case of failure.
+ */
+ if (!addr && base < highmem_start && limit > highmem_start) {
+ addr = memblock_alloc_range_nid(size, alignment,
+ highmem_start, limit, nid, true);
+ limit = highmem_start;
+ }
+
if (!addr) {
addr = memblock_alloc_range_nid(size, alignment, base,
limit, nid, true);
_
Patches currently in -mm which might be from ppbuk5246@xxxxxxxxx are
mm-cma-fix-potential-memory-loss-on-cma_declare_contiguous_nid.patch
