[merged] page-flags-prioritize-kasan-bits-over-last-cpuid.patch removed from -mm tree

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The patch titled
     Subject: page flags: prioritize kasan bits over last-cpuid
has been removed from the -mm tree.  Its filename was
     page-flags-prioritize-kasan-bits-over-last-cpuid.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: page flags: prioritize kasan bits over last-cpuid

ARM64 randdconfig builds regularly run into a build error, especially when
NUMA_BALANCING and SPARSEMEM are enabled but not SPARSEMEM_VMEMMAP:

 #error "KASAN: not enough bits in page flags for tag"

The last-cpuid bits are already contitional on the available space, so the
result of the calculation is a bit random on whether they were already
left out or not.

Adding the kasan tag bits before last-cpuid makes it much more likely to
end up with a successful build here, and should be reliable for randconfig
at least, as long as that does not randomize NR_CPUS or NODES_SHIFT but
uses the defaults.

In order for the modified check to not trigger in the x86 vdso32 code
where all constants are wrong (building with -m32), enclose all the
definitions with an #ifdef.

[arnd@xxxxxxxx: build fix]
  Link: http://lkml.kernel.org/r/CAK8P3a3Mno1SWTcuAOT0Wa9VS15pdU6EfnkxLbDpyS55yO04+g@xxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20190722115520.3743282-1-arnd@xxxxxxxx
Link: https://lore.kernel.org/lkml/20190618095347.3850490-1-arnd@xxxxxxxx/
Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/mips/vdso/vdso.h             |    1 +
 include/linux/page-flags-layout.h |   18 +++++++++++-------
 2 files changed, 12 insertions(+), 7 deletions(-)

--- a/arch/mips/vdso/vdso.h~page-flags-prioritize-kasan-bits-over-last-cpuid
+++ a/arch/mips/vdso/vdso.h
@@ -9,6 +9,7 @@
 #if _MIPS_SIM != _MIPS_SIM_ABI64 && defined(CONFIG_64BIT)
 
 /* Building 32-bit VDSO for the 64-bit kernel. Fake a 32-bit Kconfig. */
+#define BUILD_VDSO32_64
 #undef CONFIG_64BIT
 #define CONFIG_32BIT 1
 #ifndef __ASSEMBLY__
--- a/include/linux/page-flags-layout.h~page-flags-prioritize-kasan-bits-over-last-cpuid
+++ a/include/linux/page-flags-layout.h
@@ -32,6 +32,7 @@
 
 #endif /* CONFIG_SPARSEMEM */
 
+#ifndef BUILD_VDSO32_64
 /*
  * page->flags layout:
  *
@@ -76,20 +77,22 @@
 #define LAST_CPUPID_SHIFT 0
 #endif
 
-#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT <= BITS_PER_LONG - NR_PAGEFLAGS
+#ifdef CONFIG_KASAN_SW_TAGS
+#define KASAN_TAG_WIDTH 8
+#else
+#define KASAN_TAG_WIDTH 0
+#endif
+
+#if SECTIONS_WIDTH+ZONES_WIDTH+NODES_SHIFT+LAST_CPUPID_SHIFT+KASAN_TAG_WIDTH \
+	<= BITS_PER_LONG - NR_PAGEFLAGS
 #define LAST_CPUPID_WIDTH LAST_CPUPID_SHIFT
 #else
 #define LAST_CPUPID_WIDTH 0
 #endif
 
-#ifdef CONFIG_KASAN_SW_TAGS
-#define KASAN_TAG_WIDTH 8
 #if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH+LAST_CPUPID_WIDTH+KASAN_TAG_WIDTH \
 	> BITS_PER_LONG - NR_PAGEFLAGS
-#error "KASAN: not enough bits in page flags for tag"
-#endif
-#else
-#define KASAN_TAG_WIDTH 0
+#error "Not enough bits in page flags"
 #endif
 
 /*
@@ -104,4 +107,5 @@
 #define LAST_CPUPID_NOT_IN_PAGE_FLAGS
 #endif
 
+#endif
 #endif /* _LINUX_PAGE_FLAGS_LAYOUT */
_

Patches currently in -mm which might be from arnd@xxxxxxxx are

mm-sparse-fix-memory-leak-of-sparsemap_buf-in-aliged-memory-fix.patch




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