From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C183A34D4D2 for ; Sat, 18 Apr 2026 09:45:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776505508; cv=none; b=dPxnXXswQQvFnFcgoV7ZLySddfC6Yezvj2qnfbU1Q8gu6/mvPosUbcUWg39xxGp3CTYpGbLyqJ2GvJF6Nh5JuDOX1+nvRrO3AVRbreL2vwoxkY3VhHUvZ6MYH55N3l3T8Zqat7rQ//QlcfJ+yvl1dU45cD7FQ64APQRLUsF9VHo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776505508; c=relaxed/simple; bh=uzWS94xGrvHvwUyZi+5wB0p/k9w1Rf8rLHrEI6/qQdw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=P+dQSANPJWXC6/VdEfVgksr0ahJvRV9OlKd8KhhFmdhQnsQ02T9n1cNe5IfuTFPPFk3mFfG3jNy7sAtvixA8+8ChHmfIKcctbH08hX+jGifIUdyE5fjGkZ1i+zZXnVCgHWYHJ59Yj94apf/WAfI2vY3YYZ8I3ECOW2ZxV0vP47w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sOWJqKbV; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sOWJqKbV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA778C19424; Sat, 18 Apr 2026 09:45:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776505508; bh=uzWS94xGrvHvwUyZi+5wB0p/k9w1Rf8rLHrEI6/qQdw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sOWJqKbVh6LSgKpYBoov0WFLxknG+paIEGwdA7pp0XSgD97L3HDbCDW7WtyHnStJy jock4K/DL8KClznF5A2k7PYCgn29x1QgOqI0joqrTr/6LuY9ZFgKo7uMCcGHqWTs4p u7F5YVswlpFR5elcuH5nXqsjYHsvt5IBbqXxPmEUaqvYhOSYK6fU+EwbEXX48YnYm2 LVb1d4923isU8ZCfMTJqqAYdHfUlzShgamb3VGyO2DkPJRnlil50+CnorwT4WJ8wfr xozMVKS0SMUPvaGN2uqOTHKqa2kUj5BNixJsXzupmG6xQyaWoJQWVwbAS1QmkeKZbf vd42GlDMwPlhQ== Date: Sat, 18 Apr 2026 10:45:02 +0100 From: Lorenzo Stoakes To: Breno Leitao Cc: Andrew Morton , David Hildenbrand , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH v2 1/2] mm: huge_memory: use sysfs_match_string() in defrag_store() Message-ID: References: <20260408-thp_defrag-v2-0-bc544c1bde4e@debian.org> <20260408-thp_defrag-v2-1-bc544c1bde4e@debian.org> 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: <20260408-thp_defrag-v2-1-bc544c1bde4e@debian.org> On Wed, Apr 08, 2026 at 08:47:00AM -0700, Breno Leitao wrote: > Replace the if/else chain of sysfs_streq() calls in defrag_store() > with sysfs_match_string() and a defrag_mode_strings[] table. > > Introduce enum defrag_mode and defrag_flags[] array mapping each mode > to its corresponding transparent_hugepage_flag. The store function now > loops over defrag_flags[], setting the bit for the selected mode and > clearing the others. When mode is DEFRAG_NEVER (index 4), no index > in the 4-element defrag_flags[] matches, so all flags are cleared. > > Note that the enum ordering (always, defer, defer+madvise, madvise, > never) differs from the original if/else chain order in defrag_store() > (always, defer+madvise, defer, madvise, never). This is intentional to > match the display order used by defrag_show(). > > This is a follow-up cleanup to commit 522dfb4ba71f ("mm: huge_memory: > refactor anon_enabled_store() with change_anon_orders()") which applied > the same sysfs_match_string() pattern to anon_enabled_store(). > > Acked-by: David Hildenbrand (Arm) > Tested-by: Lance Yang > Reviewed-by: Lance Yang > Reviewed-by: Barry Song > Signed-off-by: Breno Leitao Thanks for doing this, big improvement! :) LGTM, so: Reviewed-by: Lorenzo Stoakes > --- > mm/huge_memory.c | 60 ++++++++++++++++++++++++++++++++------------------------ > 1 file changed, 34 insertions(+), 26 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 970e077019b75..76f2d32428c7f 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -429,6 +429,29 @@ ssize_t single_hugepage_flag_store(struct kobject *kobj, > return count; > } > > +enum defrag_mode { > + DEFRAG_ALWAYS = 0, > + DEFRAG_DEFER, > + DEFRAG_DEFER_MADVISE, > + DEFRAG_MADVISE, > + DEFRAG_NEVER, > +}; > + > +static const char * const defrag_mode_strings[] = { > + [DEFRAG_ALWAYS] = "always", > + [DEFRAG_DEFER] = "defer", > + [DEFRAG_DEFER_MADVISE] = "defer+madvise", > + [DEFRAG_MADVISE] = "madvise", > + [DEFRAG_NEVER] = "never", > +}; > + > +static const enum transparent_hugepage_flag defrag_flags[] = { > + [DEFRAG_ALWAYS] = TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, > + [DEFRAG_DEFER] = TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, > + [DEFRAG_DEFER_MADVISE] = TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, > + [DEFRAG_MADVISE] = TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, > +}; > + > static ssize_t defrag_show(struct kobject *kobj, > struct kobj_attribute *attr, char *buf) > { > @@ -456,34 +479,19 @@ static ssize_t defrag_store(struct kobject *kobj, > struct kobj_attribute *attr, > const char *buf, size_t count) > { > - if (sysfs_streq(buf, "always")) { > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); > - set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); > - } else if (sysfs_streq(buf, "defer+madvise")) { > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); > - set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); > - } else if (sysfs_streq(buf, "defer")) { > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); > - set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); > - } else if (sysfs_streq(buf, "madvise")) { > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); > - set_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); > - } else if (sysfs_streq(buf, "never")) { > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_DIRECT_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_KSWAPD_OR_MADV_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_DEFRAG_REQ_MADV_FLAG, &transparent_hugepage_flags); > - } else > + int mode, m; > + > + mode = sysfs_match_string(defrag_mode_strings, buf); > + if (mode < 0) > return -EINVAL; > > + for (m = 0; m < ARRAY_SIZE(defrag_flags); m++) { > + if (m == mode) > + set_bit(defrag_flags[m], &transparent_hugepage_flags); > + else > + clear_bit(defrag_flags[m], &transparent_hugepage_flags); > + } > + > return count; > } > static struct kobj_attribute defrag_attr = __ATTR_RW(defrag); > > -- > 2.52.0 >