From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0801D30100E for ; Fri, 22 May 2026 10:55:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779447329; cv=none; b=E7t7hl85w54ZmwgbG0ISUNN789pSY14RdrTFk4MK1YdsR2hLLEJcXoStYFpIgCw/C4dE1cIIJxS5VhRtjGZ1QppiY0wzjwbAmNbJ8eIHECPC1Ka6jpaozB0Exx+WZ4veWphZF21sniG5SEyJP7RBoX7JHRsVF7B/vk5gcohZ63A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779447329; c=relaxed/simple; bh=ZVCJFKUHcKFKOPWSG3nCcRPcln+0/bRp62tNHKWSm8I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=oQc3feyyAaxPi1q2Cflm5gQFlN4tbf4lI8p81lNo9vbwyffCyzrqtdK7YENog+JDXw5GcsHfLnr7xOV9d6wVE+PwjpUb8jOgxKHeWCW2HPtCcioeXx6c9QDTH7FzE5NO3PWXaHBWPp2z6GpmbRP4p2LfSwFwMJu6Xhih5pa/pe8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KUoZFdLU; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="KUoZFdLU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3E7C41F000E9; Fri, 22 May 2026 10:55:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779447327; bh=D7rPRt5+x/pWO5G8x4yKT/FOIc1xp6ZgAsaxw5VSqf4=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=KUoZFdLUDU9dQJPqSCO9C6gQSCR0wmQOHEkAhk6GV7lACRVbL8jphh1UpZBGmK7ek x8+5sfXZat9PV90ys5OITbORfkRnxIapxJ3lUl0oiswBsZ048Cc7D3lHrworRgt01j xoqdHBFCL17jXe/hrJczO2D4BZQOFhVBoNVLxtZS09ragaEeTvA7eMycy6vhck17RY 92BrXnNumkyhr8iHgiuwuNjtzVBjr79+NfmrtZJ1+MWfF5DDO9mRMngQio2UHQDfFZ c5Kh7adfGIhL+2cykEmCtqhOLCn1hLDPKntm6a6dVbOGMIRN1+xCah9HoAgS8boRtS 3jEbf4Rke2fTA== Date: Fri, 22 May 2026 11:55:20 +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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, May 22, 2026 at 11:39:45AM +0100, Lorenzo Stoakes wrote: > 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. Apologies, again I (somehow) missed the in-body From: :P You're good, ignore this. But do please look at the suggest below re: naming! Thanks :) > > 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 > > > >