On Fri, Jan 19, 2024 at 10:54 PM Mikhail Gavrilov
<mikhail.v.gavrilov@xxxxxxxxx> wrote:
>
I continued to search regressions in 6.8 kernel.
And found another one.
cc478e0b6bdffd20561e1a07941a65f6c8962cab is the first bad commit
commit cc478e0b6bdffd20561e1a07941a65f6c8962cab
Author: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Date: Tue Jan 9 23:12:34 2024 +0100
kasan: avoid resetting aux_lock
With commit 63b85ac56a64 ("kasan: stop leaking stack trace handles"),
KASAN zeroes out alloc meta when an object is freed. The zeroed out data
purposefully includes alloc and auxiliary stack traces but also
accidentally includes aux_lock.
As aux_lock is only initialized for each object slot during slab creation,
when the freed slot is reallocated, saving auxiliary stack traces for the
new object leads to lockdep reports when taking the zeroed out aux_lock.
Arguably, we could reinitialize aux_lock when the object is reallocated,
but a simpler solution is to avoid zeroing out aux_lock when an object
gets freed.
Link: https://lkml.kernel.org/r/20240109221234.90929-1-andrey.konovalov@xxxxxxxxx
Fixes: 63b85ac56a64 ("kasan: stop leaking stack trace handles")
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Reported-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-next/5cc0f83c-e1d6-45c5-be89-9b86746fe731@paulmck-laptop/
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Tested-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
mm/kasan/generic.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
Here I spotted a dropped FPS in the game "Shadow of the Tomb Raider".
For measuring performance I used an internal benchmark.
Before commit cc478e0b6bdffd20561e1a07941a65f6c8962cab was 111FPS on
commit aaa2c9a97c22af5bf011f6dd8e0538219b45af88 [1].
On commit cc478e0b6bdffd20561e1a07941a65f6c8962cab I has only 63FPS [2]
And unfortunately the stackdepot patchset which I applied on top of
6.8-rc2 didn't restore initial performance [3].
[1] https://i.postimg.cc/tgvwPTkz/c11-aaa2c9a97c22af5bf011f6dd8e0538219b45af88.png
[2] https://i.postimg.cc/pX8vHDCM/c10-cc478e0b6bdffd20561e1a07941a65f6c8962cab.png
[3] https://i.postimg.cc/hvWCb7dV/6-8-0-0-rc2-with-stackdepot.png
--
Best Regards,
Mike Gavrilov.
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