linux/kernel/bounds.c
Matthew Wilcox (Oracle) 93ba36238d bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS
commit 5af385f5f4 upstream.

bits_per() rounds up to the next power of two when passed a power of
two.  This causes crashes on some machines and configurations.

Reported-by: Михаил Новоселов <m.novosyolov@rosalinux.ru>
Tested-by: Ильфат Гаптрахманов <i.gaptrakhmanov@rosalinux.ru>
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3347
Link: https://lore.kernel.org/all/1c978cf1-2934-4e66-e4b3-e81b04cb3571@rosalinux.ru/
Fixes: f2d5dcb48f (bounds: support non-power-of-two CONFIG_NR_CPUS)
Cc:  <stable@vger.kernel.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-05-02 16:24:50 +02:00

29 lines
758 B
C

// SPDX-License-Identifier: GPL-2.0
/*
* Generate definitions needed by the preprocessor.
* This code generates raw asm output which is post-processed
* to extract and format the required data.
*/
#define __GENERATING_BOUNDS_H
/* Include headers that define the enum constants of interest */
#include <linux/page-flags.h>
#include <linux/mmzone.h>
#include <linux/kbuild.h>
#include <linux/log2.h>
#include <linux/spinlock_types.h>
int main(void)
{
/* The enum constants to put into include/generated/bounds.h */
DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS);
DEFINE(MAX_NR_ZONES, __MAX_NR_ZONES);
#ifdef CONFIG_SMP
DEFINE(NR_CPUS_BITS, order_base_2(CONFIG_NR_CPUS));
#endif
DEFINE(SPINLOCK_SIZE, sizeof(spinlock_t));
/* End of constants */
return 0;
}