Re: [PATCH v9 28/42] x86/shstk: Add user-mode shadow stack support

[Mark Brown]

On Mon, Jun 12, 2023 at 05:10:54PM -0700, Rick Edgecombe wrote:

> +static void unmap_shadow_stack(u64 base, u64 size)
> +{
> +	while (1) {
> +		int r;
> +
> +		r = vm_munmap(base, size);
> +
> +		/*
> +		 * vm_munmap() returns -EINTR when mmap_lock is held by
> +		 * something else, and that lock should not be held for a
> +		 * long time.  Retry it for the case.
> +		 */
> +		if (r == -EINTR) {
> +			cond_resched();
> +			continue;
> +		}

This looks generic, not even shadow stack specific - was there any
discussion of making it a vm_munmap_retry() (that's not a great name...)
or similar?  I didn't see any in old versions of the thread but I
might've missed something.

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