Anonymous shmem large order allocations are dynamically controlled via the global THP sysfs knob (/sys/kernel/mm/transparent_hugepage/shmem_enabled) and the per-size mTHP knobs (/sys/kernel/mm/transparent_hugepage/hugepages-kB/shmem_enabled). Therefore, anonymous shmem uses shmem_allowable_huge_orders() to check which large orders are allowed, rather than relying on mapping_max_folio_order(). Moreover, mapping_max_folio_order() is intended to control large order allocations only for tmpfs mounts. Clarify this by not setting a large-order range for internal anonymous shmem mappings, to avoid confusion, as discussed in the previous thread[1]. [1] https://lore.kernel.org/all/ec927492-4577-4192-8fad-85eb1bb43121@linux.alibaba.com/ Signed-off-by: Baolin Wang --- mm/shmem.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 4ecefe02881d..a60fe067969c 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3088,8 +3088,17 @@ static struct inode *__shmem_get_inode(struct mnt_idmap *idmap, if (sbinfo->noswap) mapping_set_unevictable(inode->i_mapping); - /* Don't consider 'deny' for emergencies and 'force' for testing */ - if (sbinfo->huge) + /* + * Only set the large order range for tmpfs mounts. The large order + * selection for the internal anonymous shmem mount is configured + * dynamically via the 'shmem_enabled' interfaces, so there is no + * need to set a large order range for the internal anonymous shmem + * mapping. + * + * Note: Don't consider 'deny' for emergencies and 'force' for + * testing. + */ + if (sbinfo->huge && !(sb->s_flags & SB_KERNMOUNT)) mapping_set_large_folios(inode->i_mapping); switch (mode & S_IFMT) { -- 2.47.3