This is a note to let you know that I've just added the patch titled
bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bounds-use-the-right-number-of-bits-for-power-of-two-config_nr_cpus.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5af385f5f4cddf908f663974847a4083b2ff2c79 Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Date: Mon, 29 Apr 2024 15:47:51 +0100
Subject: bounds: Use the right number of bits for power-of-two CONFIG_NR_CPUS
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From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
commit 5af385f5f4cddf908f663974847a4083b2ff2c79 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@xxxxxxxxxxxx>
Tested-by: Ильфат Гаптрахманов <i.gaptrakhmanov@xxxxxxxxxxxx>
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/3347
Link: https://lore.kernel.org/all/1c978cf1-2934-4e66-e4b3-e81b04cb3571@xxxxxxxxxxxx/
Fixes: f2d5dcb48f7b (bounds: support non-power-of-two CONFIG_NR_CPUS)
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/bounds.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/bounds.c
+++ b/kernel/bounds.c
@@ -19,7 +19,7 @@ int main(void)
DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS);
DEFINE(MAX_NR_ZONES, __MAX_NR_ZONES);
#ifdef CONFIG_SMP
- DEFINE(NR_CPUS_BITS, bits_per(CONFIG_NR_CPUS));
+ DEFINE(NR_CPUS_BITS, order_base_2(CONFIG_NR_CPUS));
#endif
DEFINE(SPINLOCK_SIZE, sizeof(spinlock_t));
/* End of constants */
Patches currently in stable-queue which might be from willy@xxxxxxxxxxxxx are
queue-5.15/bounds-use-the-right-number-of-bits-for-power-of-two-config_nr_cpus.patch
