From: Arnd Bergmann <arnd@arndb.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
Arnd Bergmann <arnd@arndb.de>,
Andrey Konovalov <andreyknvl@google.com>,
Will Deacon <will.deacon@arm.com>,
Christoph Lameter <cl@linux.com>,
Mark Rutland <mark.rutland@arm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH] [v2] page flags: prioritize kasan bits over last-cpuid
Date: Tue, 18 Jun 2019 11:53:27 +0200 [thread overview]
Message-ID: <20190618095347.3850490-1-arnd@arndb.de> (raw)
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.
Fixes: 2813b9c02962 ("kasan, mm, arm64: tag non slab memory allocated via pagealloc")
Reviewed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
Submitted v1 in March and never followed up on the build regression,
which is fixed in this version.
---
include/linux/page-flags-layout.h | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
index 1dda31825ec4..7d794a629822 100644
--- a/include/linux/page-flags-layout.h
+++ b/include/linux/page-flags-layout.h
@@ -32,6 +32,7 @@
#endif /* CONFIG_SPARSEMEM */
+#ifndef BUILD_VDSO32_64
/*
* page->flags layout:
*
@@ -76,21 +77,23 @@
#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
-#endif
/*
* We are going to use the flags for the page to node mapping if its in
@@ -104,4 +107,5 @@
#define LAST_CPUPID_NOT_IN_PAGE_FLAGS
#endif
+#endif
#endif /* _LINUX_PAGE_FLAGS_LAYOUT */
--
2.20.0
next reply other threads:[~2019-06-18 9:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-18 9:53 Arnd Bergmann [this message]
2019-06-18 14:30 ` [PATCH] [v2] page flags: prioritize kasan bits over last-cpuid Andrey Ryabinin
2019-06-18 15:30 ` Arnd Bergmann
2019-06-18 16:28 ` Andrey Ryabinin
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