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b=D009cGPJmNETl5qBLIK58SoZ3BGJmoTnIBumAi/YgRnBJ5Ag49f3w/kZyMQP4aWzN 9hBhW+FH4TGyjBLCpDIFuuGJ2dJciJG6n+bAHyHJgLhAvSda8b6sl6NMt+7xgJDDdS PuiXzk0wWNbbpxITKLsIjnk/BZR6VCFCSMkE2zbYsqWNEI1CoQq18wVcgWGjIxDWi8 sn73Qjp7LOl243STYm1mxrYRhNd3dD0iyzGL4iSxRl3Wu9T8TTXpjqu0+J3e67lFqE Z8FXaY/ILsmYzsQxDbk2QlB7FMQLrKC2bfnMSN1CWXjpTUdIJQpL9/nNURd1XhyG7m F2wuDP2xVVtLA== Date: Fri, 22 May 2026 11:39:39 +0100 From: Lorenzo Stoakes To: ranxiaokai627@163.com Cc: hughd@google.com, baolin.wang@linux.alibaba.com, akpm@linux-foundation.org, leitao@debian.org, ziy@nvidia.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, david@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ran.xiaokai@zte.com.cn Subject: Re: [PATCH v3 1/2] mm: shmem: refactor thpsize_shmem_enabled_store() with sysfs_match_string() Message-ID: References: <20260518123238.56344-1-ranxiaokai627@163.com> <20260518123238.56344-2-ranxiaokai627@163.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260518123238.56344-2-ranxiaokai627@163.com> X-Stat-Signature: wimwegjmsdcj1nnyswmxu1mb9ai5okpq X-Rspamd-Queue-Id: 20199180005 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1779446386-751769 X-HE-Meta: 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 XzHVvURu LPIBUnPRKi2nh/o/RoY9+hF3H74ttS9H/7zfz3YsRT/xUj+YGYTZh7ec1HPyaYlmUHchJ/m2f6wN/SSTrLDxqXHF3AAVVfl560zL++xEY8IMG930b5WK1LkXtrihx84qQSmVhr2OZaOUtvI7P0xnzuJrTbEfb4+uyAXIESrYzupxZJl5edvP3qWnKMuso/h5fssoqjPzFqCnKMXVS9DnZftruxaGq/qzYdlXRxTeRRlS9Kk0Fo5wAhyG2lX2WRXpPKS0puTAHSgfTwIqz8sZBvQQDnYgWhDWjK1Q7rDEpTah8pIyyGm1LgonPV2d90hkgyqgJY47sT4fRNVGHT+AhFleD8DxHl2/sd6BV2rN2K+aikW2TOHS7iAwAnUBiKN+ALoBX Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, May 18, 2026 at 12:32:37PM +0000, ranxiaokai627@163.com wrote: > From: Ran Xiaokai > > Inspired by commit 82d9ff648c6c ("mm: huge_memory: refactor > anon_enabled_store() with set_anon_enabled_mode()"), refactor > thpsize_shmem_enabled_store() using sysfs_match_string(). > This eliminates the duplicated spin_lock/unlock(), set/clear_bit(), > calls across all branches, reducing code duplication. > > Behavioral change: > Call start_stop_khugepaged() only when the mode actually changes. > If unchanged, call set_recommended_min_free_kbytes() to preserve > legacy watermark behavior. This avoids unnecessary khugepaged restarts. > > Tested with selftests ./run_kselftest.sh -t mm:ksft_thp.sh, > all test cases passed. > > Signed-off-by: Ran Xiaokai Your From: and Signed-off-by: differs. As per my mail to the 2/2 this violates kernel process rules. Please either update the signed-off-by to your @163.com address or resend from your zte.com.cn address. Logic generally looks good, but you need to fix your From/Signed-off-by and the rename suggested below would be good. Thanks, Lorenzo > --- > mm/shmem.c | 107 ++++++++++++++++++++++++++++++----------------------- > 1 file changed, 60 insertions(+), 47 deletions(-) > > diff --git a/mm/shmem.c b/mm/shmem.c > index 3b5dc21b323c..46d2cfc30823 100644 > --- a/mm/shmem.c > +++ b/mm/shmem.c > @@ -5526,6 +5526,29 @@ static ssize_t shmem_enabled_store(struct kobject *kobj, > struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled); > static DEFINE_SPINLOCK(huge_shmem_orders_lock); > > +enum huge_shmem_enabled_mode { > + HUGE_SHMEM_ENABLED_ALWAYS = 0, > + HUGE_SHMEM_ENABLED_INHERIT, > + HUGE_SHMEM_ENABLED_WITHIN_SIZE, > + HUGE_SHMEM_ENABLED_ADVISE, > + HUGE_SHMEM_ENABLED_NEVER, > +}; > + > +static const char * const huge_shmem_enabled_mode_strings[] = { > + [HUGE_SHMEM_ENABLED_ALWAYS] = "always", > + [HUGE_SHMEM_ENABLED_INHERIT] = "inherit", > + [HUGE_SHMEM_ENABLED_WITHIN_SIZE] = "within_size", > + [HUGE_SHMEM_ENABLED_ADVISE] = "advise", > + [HUGE_SHMEM_ENABLED_NEVER] = "never", > +}; > + > +static unsigned long * const huge_shmem_orders_by_mode[] = { > + [HUGE_SHMEM_ENABLED_ALWAYS] = &huge_shmem_orders_always, > + [HUGE_SHMEM_ENABLED_INHERIT] = &huge_shmem_orders_inherit, > + [HUGE_SHMEM_ENABLED_WITHIN_SIZE] = &huge_shmem_orders_within_size, > + [HUGE_SHMEM_ENABLED_ADVISE] = &huge_shmem_orders_madvise, > +}; As Baolin suggested, we can probably rename these for bervity. We know it's shmem, as it's in shmem.c :) so drop that. huge_mode, huge_mode_strings, huge_mode_orders seems good to me? > + > static ssize_t thpsize_shmem_enabled_show(struct kobject *kobj, > struct kobj_attribute *attr, char *buf) > { > @@ -5546,63 +5569,53 @@ static ssize_t thpsize_shmem_enabled_show(struct kobject *kobj, > return sysfs_emit(buf, "%s\n", output); > } > > +static bool set_shmem_enabled_mode(int order, enum huge_shmem_enabled_mode mode) > +{ > + bool changed = false; > + enum huge_shmem_enabled_mode idx; > + > + spin_lock(&huge_shmem_orders_lock); > + for (idx = 0; idx < ARRAY_SIZE(huge_shmem_orders_by_mode); idx++) { > + if (idx == mode) > + changed |= !__test_and_set_bit(order, huge_shmem_orders_by_mode[idx]); > + else > + changed |= __test_and_clear_bit(order, huge_shmem_orders_by_mode[idx]); > + } > + spin_unlock(&huge_shmem_orders_lock); > + > + return changed; > +} > + Thanks for separating this out! :) > static ssize_t thpsize_shmem_enabled_store(struct kobject *kobj, > struct kobj_attribute *attr, > const char *buf, size_t count) > { > int order = to_thpsize(kobj)->order; > - ssize_t ret = count; > - > - if (sysfs_streq(buf, "always")) { > - spin_lock(&huge_shmem_orders_lock); > - clear_bit(order, &huge_shmem_orders_inherit); > - clear_bit(order, &huge_shmem_orders_madvise); > - clear_bit(order, &huge_shmem_orders_within_size); > - set_bit(order, &huge_shmem_orders_always); > - spin_unlock(&huge_shmem_orders_lock); > - } else if (sysfs_streq(buf, "inherit")) { > - /* Do not override huge allocation policy with non-PMD sized mTHP */ > - if (shmem_huge == SHMEM_HUGE_FORCE && !is_pmd_order(order)) > - return -EINVAL; > + int mode; > > - spin_lock(&huge_shmem_orders_lock); > - clear_bit(order, &huge_shmem_orders_always); > - clear_bit(order, &huge_shmem_orders_madvise); > - clear_bit(order, &huge_shmem_orders_within_size); > - set_bit(order, &huge_shmem_orders_inherit); > - spin_unlock(&huge_shmem_orders_lock); > - } else if (sysfs_streq(buf, "within_size")) { > - spin_lock(&huge_shmem_orders_lock); > - clear_bit(order, &huge_shmem_orders_always); > - clear_bit(order, &huge_shmem_orders_inherit); > - clear_bit(order, &huge_shmem_orders_madvise); > - set_bit(order, &huge_shmem_orders_within_size); > - spin_unlock(&huge_shmem_orders_lock); > - } else if (sysfs_streq(buf, "advise")) { > - spin_lock(&huge_shmem_orders_lock); > - clear_bit(order, &huge_shmem_orders_always); > - clear_bit(order, &huge_shmem_orders_inherit); > - clear_bit(order, &huge_shmem_orders_within_size); > - set_bit(order, &huge_shmem_orders_madvise); > - spin_unlock(&huge_shmem_orders_lock); > - } else if (sysfs_streq(buf, "never")) { > - spin_lock(&huge_shmem_orders_lock); > - clear_bit(order, &huge_shmem_orders_always); > - clear_bit(order, &huge_shmem_orders_inherit); > - clear_bit(order, &huge_shmem_orders_within_size); > - clear_bit(order, &huge_shmem_orders_madvise); > - spin_unlock(&huge_shmem_orders_lock); > - } else { > - ret = -EINVAL; > - } > + mode = sysfs_match_string(huge_shmem_enabled_mode_strings, buf); > + if (mode < 0) > + return mode; > > - if (ret > 0) { > - int err = start_stop_khugepaged(); > + /* Do not override huge allocation policy with non-PMD sized mTHP */ > + if (mode == HUGE_SHMEM_ENABLED_INHERIT && > + shmem_huge == SHMEM_HUGE_FORCE && !is_pmd_order(order)) > + return -EINVAL; > > + if (set_shmem_enabled_mode(order, mode)) { > + int err = start_stop_khugepaged(); > if (err) > - ret = err; > + return err; > + } else { > + /* > + * Recalculate watermarks even when the mode hasn't changed > + * to preserve the legacy behavior, as this is always called > + * inside start_stop_khugepaged(). > + */ > + set_recommended_min_free_kbytes(); > } > - return ret; > + > + return count; > } > > struct kobj_attribute thpsize_shmem_enabled_attr = > -- > 2.25.1 > >