6.6-stable review patch. If anyone has any objections, please let me know.
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From: Michael Ellerman mpe@ellerman.id.au
commit 18f14afe281648e31ed35c9ad2fcb724c4838ad9 upstream.
There are reports of kernels crashing due to stack overflow while running OpenShift (Kubernetes). The primary contributor to the stack usage seems to be openvswitch, which is used by OVN-Kubernetes (based on OVN (Open Virtual Network)), but NFS also contributes in some stack traces.
There may be some opportunities to reduce stack usage in the openvswitch code, but doing so potentially require tradeoffs vs performance, and also requires testing across architectures.
Looking at stack usage across the kernel (using -fstack-usage), shows that ppc64le stack frames are on average 50-100% larger than the equivalent function built for x86-64. Which is not surprising given the minimum stack frame size is 32 bytes on ppc64le vs 16 bytes on x86-64.
So increase the default stack size to 32KB for the modern 64-bit Book3S platforms, ie. pseries (virtualised) and powernv (bare metal). That leaves the older systems like G5s, and the AmigaOne (pasemi) with a 16KB stack which should be sufficient on those machines.
Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Aneesh Kumar K.V (IBM) aneesh.kumar@kernel.org Link: https://msgid.link/20231215124449.317597-1-mpe@ellerman.id.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/Kconfig | 1 + 1 file changed, 1 insertion(+)
--- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -857,6 +857,7 @@ config THREAD_SHIFT int "Thread shift" if EXPERT range 13 15 default "15" if PPC_256K_PAGES + default "15" if PPC_PSERIES || PPC_POWERNV default "14" if PPC64 default "13" help