Subject: Re: [PATCH 0/3] IRQ stack support for ARM

From: Russell King - ARM Linux admin <[email-masked]>
Date: Thu, 8 Oct 2020 09:30:15 +0100

On Thu, Oct 08, 2020 at 12:45:30PM +0530, Maninder Singh wrote:
> Observed Stack Overflow on 8KB kernel stack on ARM specially 
> incase on network interrupts, which results in undeterministic behaviour. 
> So there is need for per cpu dedicated IRQ stack for ARM.
> 
> As ARm does not have extra co-processor register
> to save thread info pointer, IRQ stack will be at some
> performance cost, so code is under CONFIG_IRQ_STACK.
> 
> and we don't have much knowledge and set up for CLANG
> and ARM_UNWIND, so dependency added for both cases.
> 
> Tested patch set with QEMU for latest kernel
> and 4.1 kernel for ARM target with same patch set.

You need to investigate and show where and why this is happening. My
guess is you have a network driver that uses a lot of kernel stack
space, which itself would be a bug.

Note that there are compiler versions out there that mis-optimise and
eat stack space - the kernel build should be warning if a function
uses a large amount of stack.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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