Re: [PATCH v8 3/5] arm64: mm: support large block mapping when rodata=full

[Guenter Roeck]

On 11/2/25 09:49, Guenter Roeck wrote:
> On Sun, Nov 2, 2025 at 7:09 AM Ryan Roberts <linux@xxxxxxxxxxxx> wrote:

Oops. That was sent from my Google address and got messed up.
Copying Ryan this time. Sorry for the noise.

Guenter

> ...
> > commit 602ec2db74e5abfb058bd03934475ead8558eb72
> > Author: Ryan Roberts <ryan.roberts@xxxxxxx>
> > Date:   Sun Nov 2 11:45:18 2025 +0000
> >
> >      arm64: mm: Don't attempt to split known pte-mapped regions
> >
> >      It has been reported that split_kernel_leaf_mapping() is trying to sleep
> >      in non-sleepable context. It does this when acquiring the
> >      pgtable_split_lock mutex, when either CONFIG_DEBUG_ALLOC or
> >      CONFIG_KFENCE are enabled, which change linear map permissions within
> >      softirq context during memory allocation and/or freeing.
> >
> >      But it turns out that the memory for which these features may attempt to
> >      modify the permissions is always mapped by pte, so there is no need to
> >      attempt to split the mapping. So let's exit early in these cases and
> >      avoid attempting to take the mutex.
> >
> >      Closes: https://lore.kernel.org/all/f24b9032-0ec9-47b1-8b95-c0eeac7a31c5@xxxxxxxxxxxx/
> >      Fixes: a166563e7ec3 ("arm64: mm: support large block mapping when rodata=full")
> >      Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
>
> Tested-by: Guenter Roeck <groeck@xxxxxxxxxx>
>
> Thanks a lot for the quick turnaround!
>
> Guenter