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Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0X13xQlN_1776241386 cluster:ay36) by smtp.aliyun-inc.com; Wed, 15 Apr 2026 16:23:07 +0800 From: Baolin Wang To: akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, ziy@nvidia.com, david@kernel.org, ljs@kernel.org, lance.yang@linux.dev, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] mm: shmem: don't set large-order range for internal shmem mount Date: Wed, 15 Apr 2026 16:22:53 +0800 Message-ID: X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: CB271140002 X-Stat-Signature: g7dy76n1hj9xtkifxswkhabyiar6gtqj X-Rspam-User: X-HE-Tag: 1776241392-419530 X-HE-Meta: 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 +Zz5oOYc KLBxKFAz9My3dIi9c+q1LrS1NLB/Na9EpvUGZKgnjLisA/Oscow+ky+rvASJ5y1DNj+52xRLJqIHo1LbX6LESgmvbiOl9ZpxPuqx87DsOD5v8vGkqLMJ1z3dTfXGXct7kABP8Zvv6fptTzjXHXFBWsAvbO3m0rFXeH8IZDhTdFl8BWWmWMRK3OdpEyQq7Hczzn8uiUM/SOPpFR/z1RegWfxuT1whEGb7X+yglaol2QPrsdPaxDAhk0L2iLAZB5H+lKWC3XGWW4iTcJVme2g2xkpaNOA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 shmem mount (e.g. anonymous shmem), 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 --- Changes from v1: - Update the comments and commit message, per Lance. --- mm/shmem.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 4ecefe02881d..568e1baee90d 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -3088,8 +3088,16 @@ 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 shmem mount is configured dynamically + * via the 'shmem_enabled' interfaces, so there is no need to set a + * large order range for the internal shmem mount's 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