diff mbox series

[12/16] mm, kasan: fix __GFP_BITS_SHIFT definition breaking LOCKDEP

Message ID 20220401182846.53FD5C2BBE4@smtp.kernel.org (mailing list archive)
State New
Headers show
Series [01/16] Revert "mm: madvise: skip unmapped vma holes passed to process_madvise" | expand

Commit Message

Andrew Morton April 1, 2022, 6:28 p.m. UTC 
From: Andrey Konovalov <andreyknvl@google.com>
Subject: mm, kasan: fix __GFP_BITS_SHIFT definition breaking LOCKDEP

KASAN changes that added new GFP flags mistakenly updated __GFP_BITS_SHIFT
as the total number of GFP bits instead of as a shift used to define
__GFP_BITS_MASK.

This broke LOCKDEP, as __GFP_BITS_MASK now gets the 25th bit enabled
instead of the 28th for __GFP_NOLOCKDEP.

Update __GFP_BITS_SHIFT to always count KASAN GFP bits.

In the future, we could handle all combinations of KASAN and LOCKDEP to
occupy as few bits as possible.  For now, we have enough GFP bits to be
inefficient in this quick fix.

Link: https://lkml.kernel.org/r/462ff52742a1fcc95a69778685737f723ee4dfb3.1648400273.git.andreyknvl@google.com
Fixes: 9353ffa6e9e9 ("kasan, page_alloc: allow skipping memory init for HW_TAGS")
Fixes: 53ae233c30a6 ("kasan, page_alloc: allow skipping unpoisoning for HW_TAGS")
Fixes: f49d9c5bb15c ("kasan, mm: only define ___GFP_SKIP_KASAN_POISON with HW_TAGS")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/gfp.h |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff mbox series

Patch

--- a/include/linux/gfp.h~mm-kasan-fix-__gfp_bits_shift-definition-breaking-lockdep
+++ a/include/linux/gfp.h
@@ -264,9 +264,7 @@  struct vm_area_struct;
 #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
 
 /* Room for N __GFP_FOO bits */
-#define __GFP_BITS_SHIFT (24 +						\
-			  3 * IS_ENABLED(CONFIG_KASAN_HW_TAGS) +	\
-			  IS_ENABLED(CONFIG_LOCKDEP))
+#define __GFP_BITS_SHIFT (27 + IS_ENABLED(CONFIG_LOCKDEP))
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /**