This is a note to let you know that I've just added the patch titled powerpc/kcsan: Exclude udelay to prevent recursive instrumentation to the 6.2-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: powerpc-kcsan-exclude-udelay-to-prevent-recursive-in.patch and it can be found in the queue-6.2 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f781c4af116ee28c5d3d0081a8d5715d16ab74c4 Author: Rohan McLure <rmclure@xxxxxxxxxxxxx> Date: Mon Feb 6 13:17:58 2023 +1100 powerpc/kcsan: Exclude udelay to prevent recursive instrumentation [ Upstream commit 2a7ce82dc46c591c9244057d89a6591c9639b9b9 ] In order for KCSAN to increase its likelihood of observing a data race, it sets a watchpoint on memory accesses and stalls, allowing for detection of conflicting accesses by other kernel threads or interrupts. Stalls are implemented by injecting a call to udelay in instrumented code. To prevent recursive instrumentation, exclude udelay from being instrumented. Signed-off-by: Rohan McLure <rmclure@xxxxxxxxxxxxx> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20230206021801.105268-3-rmclure@xxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index e26eb6618ae5d..9d8665910350c 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -356,7 +356,7 @@ void vtime_flush(struct task_struct *tsk) } #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ -void __delay(unsigned long loops) +void __no_kcsan __delay(unsigned long loops) { unsigned long start; @@ -377,7 +377,7 @@ void __delay(unsigned long loops) } EXPORT_SYMBOL(__delay); -void udelay(unsigned long usecs) +void __no_kcsan udelay(unsigned long usecs) { __delay(tb_ticks_per_usec * usecs); }