Re: [GIT PULL] vfs mount api updates

[Will Deacon]

Hi Linus,

On Mon, Jan 08, 2024 at 05:02:48PM -0800, Linus Torvalds wrote:
> On Fri, 5 Jan 2024 at 04:47, Christian Brauner <brauner@xxxxxxxxxx> wrote:
> >
> > This contains the work to retrieve detailed information about mounts via two
> > new system calls.
> 
> Gaah. While I have an arm64 laptop now, I don't do arm64 builds in
> between each pull like I do x86 ones.
> 
> I *did* just start one, because I got the arm64 pull request.
> 
> And this fails the arm64 build, because __NR_statmount and
> __NR_listmount (457 and 458 respectively) exceed the compat system
> call array size, which is
> 
> arch/arm64/include/asm/unistd.h:
>   #define __NR_compat_syscalls            457
> 
> I don't think this is a merge error, I think the error is there in the
> original, but I'm about to go off and have dinner, so I'm just sending
> this out for now.
> 
> How was this not noted in linux-next? Am I missing something?

Urgh, that is surprising, and I just confirmed that linux-next builds
fine! The reason seems to be because there are also some new lsm
syscalls being added there (lsm_get_self_attr and friends) which bump
__NR_compat_syscalls to 460 and then Stephen Rothwell's mighty merging
magic adjusted this up to 462 in the merge of the lsm tree.

> Now, admittedly this looks like an easy mistake to make due to that
> whole odd situation where the compat system calls are listed in
> unistd32.h, but then the max number is in unistd.h, but I would still
> have expected this to have raised flags before it hit my tree..

I suppose the two options for now are either to merge the lsm stuff and
adjust __NR_compat_syscalls as Stephen did, or to take this patch from
Florian in the meantime:

https://lore.kernel.org/r/20240109010906.429652-1-florian.fainelli@xxxxxxxxxxxx

Cheers,

Will