Re: [PATCH 1/4] xfs: use kvmalloc for xattr buffers

Pankaj Raghav (Samsung)
2024-04-17T14:35:28Z

> Pankaj Raghav reported that when filesystem block size is larger
> than page size, the xattr code can use kmalloc() for high order
> allocations. This triggers a useless warning in the allocator as it
> is a __GFP_NOFAIL allocation here:
>
> static inline
> struct page *rmqueue(struct zone *preferred_zone,
> struct zone *zone, unsigned int order,
> gfp_t gfp_flags, unsigned int alloc_flags,
> int migratetype)
> {
> struct page *page;
>
> /*
> * We most definitely don't want callers attempting to
> * allocate greater than order-1 page units with __GFP_NOFAIL.
> */
> >>>> WARN_ON_ONCE((gfp_flags & __GFP_NOFAIL) && (order > 1));
> ...
>
> Fix this by changing all these call sites to use kvmalloc(), which
> will strip the NOFAIL from the kmalloc attempt and if that fails
> will do a __GFP_NOFAIL vmalloc().
>
> This is not an issue that productions systems will see as
> filesystems with block size > page size cannot be mounted by the
> kernel; Pankaj is developing this functionality right now.
>
> Reported-by: Pankaj Raghav <kernel@pankajraghav.com>
> Fixes: f078d4ea8276 ("xfs: convert kmem_alloc() to kmalloc()")
> Signed-off-be: Dave Chinner <dchinner@redhat.com>

Thanks. I tested this patch in my LBS branch and it fixes the warning.

Reviewed-by: Pankaj Raghav <p.raghav@samsung.com>

For now, I will add it to my LBS branch as I don't see it yet land on
6.9-rcs.

> ---
> fs/xfs/libxfs/xfs_attr_leaf.c | 15 ++++++---------
> 1 file changed, 6 insertions(+), 9 deletions(-)

--
Pankaj