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 C8A37364E9F for ; Tue, 17 Mar 2026 17:15:21 +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=1773767721; cv=none; b=itsUWYx7ylBNL0Qzd+6Ys35G4ebq4j1WiMOE74N9vlBOdOJy4gmzO/B2nNEY45fMRU2hUroV22GNBlXwvt4cITq8FOyj1gE+Brc302nqsA6/iqMn2YBDpXCriLUYbltmZURRGZ6nSZXqSrjC1cU4p3oQGtzf4c08a65jZwZ/Ug8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773767721; c=relaxed/simple; bh=LNGH6ATNSFZJFkqeWmeL04zhQgwzX7ztcGi3iYyEbjo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=UjZ2dBUGxvKQ/4igsxfP4z2CxyN0kqPFPBy+oejbRDK1S6afRj8GSKhcTP5eE2abb91+Tg821avjTEsfcp/EJdQm1VDf8IW960mIAmBLrEJTxWEEEpJV5uMkNc3gBNRfSEUzwim5aQF5rUWbZi2kuZYRBKWqArf4UcWBJunMtaQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=R7yBfzxO; 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="R7yBfzxO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6536CC2BCB0; Tue, 17 Mar 2026 17:15:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1773767721; bh=LNGH6ATNSFZJFkqeWmeL04zhQgwzX7ztcGi3iYyEbjo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=R7yBfzxOxg0w/kBFFlEjimCfZnorLz2V68eS6pAfraBg9BPGVUjdmB04cVOeOPovT OwdtbfNR+39B/8BgknTto+7sD7BRzPA+uo+soWyAJzISSCLHqx0kNRgiBU+z07rsy0 jbBmQvn9gJqa3Tv+2TPZNunMsb0B7wV1bo5cM/xgBxl5UvV4ect/4LU4h+kzUlSL3e N3pjyf8e9AqtJlR0LQCusQHCBKG4W5kzfAU6kbNM+is0ijbkKL1rno1Ftu9v6NOcnu gX55BE8jvBTQRTaIEZ83TQGJN+qyH/RJJze370XE8JkQ4AtWp0JW4O7FkQCz5kp8WS 4WtzcOfkWM6Bw== Date: Tue, 17 Mar 2026 17:15:14 +0000 From: "Lorenzo Stoakes (Oracle)" To: Breno Leitao Cc: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Zi Yan , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Mike Rapoport , linux-mm@kvack.org, linux-kernel@vger.kernel.org, usamaarif642@gmail.com, kas@kernel.org, kernel-team@meta.com, Wei Yang Subject: Re: [PATCH v7 3/4] mm: huge_memory: refactor enabled_store() with set_global_enabled_mode() Message-ID: References: <20260317-thp_logs-v7-0-31eb98fa5a8b@debian.org> <20260317-thp_logs-v7-3-31eb98fa5a8b@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: <20260317-thp_logs-v7-3-31eb98fa5a8b@debian.org> On Tue, Mar 17, 2026 at 08:33:58AM -0700, Breno Leitao wrote: > Refactor enabled_store() to use a new set_global_enabled_mode() helper. > Introduce a separate enum global_enabled_mode and > global_enabled_mode_strings[], mirroring the anon_enabled_mode > pattern from the previous commit. > > A separate enum is necessary because the global THP setting does > not support "inherit", only "always", "madvise", and "never". > Reusing anon_enabled_mode would leave a NULL gap in the string > array, causing sysfs_match_string() to stop early and fail to > match entries after the gap. > > The helper uses the same loop pattern as set_anon_enabled_mode(), > iterating over an array of flag bit positions and using > test_and_set_bit()/test_and_clear_bit() to track whether the state > actually changed. > > Reviewed-by: Lorenzo Stoakes (Oracle) > Reviewed-by: Zi Yan > Reviewed-by: Baolin Wang > Reviewed-by: Wei Yang > Signed-off-by: Breno Leitao > --- > mm/huge_memory.c | 63 ++++++++++++++++++++++++++++++++++++++++++-------------- > 1 file changed, 48 insertions(+), 15 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index f6af90e6cf05d..b95fde5843399 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -330,30 +330,63 @@ static const char * const anon_enabled_mode_strings[] = { > [ANON_ENABLED_NEVER] = "never", > }; > > +enum global_enabled_mode { > + GLOBAL_ENABLED_ALWAYS = 0, > + GLOBAL_ENABLED_MADVISE = 1, > + GLOBAL_ENABLED_NEVER = 2, > +}; > + > +static const char * const global_enabled_mode_strings[] = { > + [GLOBAL_ENABLED_ALWAYS] = "always", > + [GLOBAL_ENABLED_MADVISE] = "madvise", > + [GLOBAL_ENABLED_NEVER] = "never", > +}; > + > +static bool set_global_enabled_mode(enum global_enabled_mode mode) > +{ > + static const unsigned long thp_flags[] = { > + TRANSPARENT_HUGEPAGE_FLAG, > + TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, > + }; > + enum global_enabled_mode m; > + bool changed = false; > + > + for (m = 0; m < ARRAY_SIZE(thp_flags); m++) { > + if (m == mode) > + changed |= !test_and_set_bit(thp_flags[m], > + &transparent_hugepage_flags); > + else > + changed |= test_and_clear_bit(thp_flags[m], > + &transparent_hugepage_flags); LGTM! > + } > + > + return changed; > +} > + > static ssize_t enabled_store(struct kobject *kobj, > struct kobj_attribute *attr, > const char *buf, size_t count) > { > - ssize_t ret = count; > + int mode; > > - if (sysfs_streq(buf, "always")) { > - clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); > - set_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); > - } else if (sysfs_streq(buf, "madvise")) { > - clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); > - set_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); > - } else if (sysfs_streq(buf, "never")) { > - clear_bit(TRANSPARENT_HUGEPAGE_FLAG, &transparent_hugepage_flags); > - clear_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG, &transparent_hugepage_flags); > - } else > - ret = -EINVAL; > + mode = sysfs_match_string(global_enabled_mode_strings, buf); > + if (mode < 0) > + return -EINVAL; > > - if (ret > 0) { > + if (set_global_enabled_mode(mode)) { > int err = start_stop_khugepaged(); > + > if (err) > - ret = err; > + return err; > + } else { > + /* > + * Recalculate watermarks even when the mode didn't > + * change, as the previous code always called > + * start_stop_khugepaged() which does this internally. > + */ > + set_recommended_min_free_kbytes(); > } > - return ret; > + return count; > } > > static struct kobj_attribute enabled_attr = __ATTR_RW(enabled); > > -- > 2.52.0 >