Re: Re: [PATCH v2] tmpfs: fault in smaller chunks if large folio allocation not allowed

[Matthew Wilcox <willy@infradead.org>]

On Thu, Sep 26, 2024 at 10:38:34AM +0200, Pankaj Raghav (Samsung) wrote:
> > So this is why I don't use mapping_set_folio_order_range() here, but
> > correct me if I am wrong.
> 
> Yeah, the inode is active here as the max folio size is decided based on
> the write size, so probably mapping_set_folio_order_range() will not be
> a safe option.

You really are all making too much of this.  Here's the patch I think we
need:

+++ b/mm/shmem.c
@@ -2831,7 +2831,8 @@ static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
        cache_no_acl(inode);
        if (sbinfo->noswap)
                mapping_set_unevictable(inode->i_mapping);
-       mapping_set_large_folios(inode->i_mapping);
+       if (sbinfo->huge)
+               mapping_set_large_folios(inode->i_mapping);

        switch (mode & S_IFMT) {
        default: