The patch titled
Subject: vmalloc: fix __GFP_HIGHMEM usage for vmalloc_32 on 32b systems
has been added to the -mm tree. Its filename is
vmalloc-fix-__gfp_highmem-usage-for-vmalloc_32-on-32b-systems.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/vmalloc-fix-__gfp_highmem-usage-for-vmalloc_32-on-32b-systems.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/vmalloc-fix-__gfp_highmem-usage-for-vmalloc_32-on-32b-systems.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxx>
Subject: vmalloc: fix __GFP_HIGHMEM usage for vmalloc_32 on 32b systems
Kai Heng Feng has noticed that BUG_ON(PageHighMem(pg)) triggers in
drivers/media/common/saa7146/saa7146_core.c since 19809c2da28a ("mm,
vmalloc: use __GFP_HIGHMEM implicitly"). saa7146_vmalloc_build_pgtable
uses vmalloc_32 and it is reasonable to expect that the resulting page is
not in highmem. The above commit aimed to add __GFP_HIGHMEM only for
those requests which do not specify any zone modifier gfp flag.
vmalloc_32 relies on GFP_VMALLOC32 which should do the right thing.
Except it has been missed that GFP_VMALLOC32 is an alias for GFP_KERNEL on
32b architectures. Thanks to Matthew to notice this.
Fix the problem by unconditionally setting GFP_DMA32 in GFP_VMALLOC32 for
!64b arches (as a bailout). This should do the right thing and use
ZONE_NORMAL which should be always below 4G on 32b systems.
Debugged by Matthew Wilcox.
Link: http://lkml.kernel.org/r/20180212095019.GX21609@xxxxxxxxxxxxxx
Fixes: 19809c2da28a ("mm, vmalloc: use __GFP_HIGHMEM implicitly”)
Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
Reported-by: Kai Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff -puN mm/vmalloc.c~vmalloc-fix-__gfp_highmem-usage-for-vmalloc_32-on-32b-systems mm/vmalloc.c
--- a/mm/vmalloc.c~vmalloc-fix-__gfp_highmem-usage-for-vmalloc_32-on-32b-systems
+++ a/mm/vmalloc.c
@@ -1947,7 +1947,11 @@ void *vmalloc_exec(unsigned long size)
#elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
#define GFP_VMALLOC32 GFP_DMA | GFP_KERNEL
#else
-#define GFP_VMALLOC32 GFP_KERNEL
+/*
+ * 64b systems should always have either DMA or DMA32 zones. For others
+ * GFP_DMA32 should do the right thing and use the normal zone.
+ */
+#define GFP_VMALLOC32 GFP_DMA32 | GFP_KERNEL
#endif
/**
_
Patches currently in -mm which might be from mhocko@xxxxxxxx are
vmalloc-fix-__gfp_highmem-usage-for-vmalloc_32-on-32b-systems.patch
mm-oom-docs-describe-the-cgroup-aware-oom-killer-fix-2.patch
mm-introduce-map_fixed_safe.patch
fs-elf-drop-map_fixed-usage-from-elf_map.patch
mm-numa-rework-do_pages_move.patch
mm-migrate-remove-reason-argument-from-new_page_t.patch
mm-unclutter-thp-migration.patch