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Tue, 10 Mar 2026 20:12:30 -0700 (PDT) Date: Wed, 11 Mar 2026 03:12:29 +0000 From: Wei Yang 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, "Lorenzo Stoakes (Oracle)" Subject: Re: [PATCH v5 2/4] mm: huge_memory: refactor anon_enabled_store() with change_anon_orders() Message-ID: <20260311031229.mloqvlmmqipr7k2h@master> Reply-To: Wei Yang References: <20260310-thp_logs-v5-0-686099175bf6@debian.org> <20260310-thp_logs-v5-2-686099175bf6@debian.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260310-thp_logs-v5-2-686099175bf6@debian.org> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Queue-Id: C9C84C0005 X-Rspamd-Server: rspam07 X-Stat-Signature: eans8qoq4sr7ekiaid5g37c6cyk89zpo X-Rspam-User: X-HE-Tag: 1773198752-801745 X-HE-Meta: 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 Vvgb0sZ8 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Mar 10, 2026 at 10:57:08AM -0700, Breno Leitao wrote: >Consolidate the repeated spin_lock/set_bit/clear_bit pattern in >anon_enabled_store() into a new change_anon_orders() helper that >loops over an orders[] array, setting the bit for the selected mode >and clearing the others. > >Introduce enum anon_enabled_mode and anon_enabled_mode_strings[] >for the per-order anon THP setting. > >Use sysfs_match_string() with the anon_enabled_mode_strings[] table >to replace the if/else chain of sysfs_streq() calls. > >The helper uses test_and_set_bit()/test_and_clear_bit() to track >whether the state actually changed, so start_stop_khugepaged() is >only called when needed. When the mode is unchanged, >set_recommended_min_free_kbytes() is called directly to preserve >the watermark recalculation behavior of the original code. > >Signed-off-by: Breno Leitao >Reviewed-by: Lorenzo Stoakes (Oracle) >--- > mm/huge_memory.c | 84 +++++++++++++++++++++++++++++++++++--------------------- > 1 file changed, 52 insertions(+), 32 deletions(-) > >diff --git a/mm/huge_memory.c b/mm/huge_memory.c >index 8e2746ea74adf..e19dda5aaf195 100644 >--- a/mm/huge_memory.c >+++ b/mm/huge_memory.c >@@ -316,6 +316,20 @@ static ssize_t enabled_show(struct kobject *kobj, > return sysfs_emit(buf, "%s\n", output); > } > >+enum anon_enabled_mode { >+ ANON_ENABLED_ALWAYS = 0, >+ ANON_ENABLED_MADVISE = 1, >+ ANON_ENABLED_INHERIT = 2, >+ ANON_ENABLED_NEVER = 3, >+}; >+ >+static const char * const anon_enabled_mode_strings[] = { >+ [ANON_ENABLED_ALWAYS] = "always", >+ [ANON_ENABLED_MADVISE] = "madvise", >+ [ANON_ENABLED_INHERIT] = "inherit", >+ [ANON_ENABLED_NEVER] = "never", >+}; >+ Just one trivial thing, maybe keep the sequence as the sysfs output? Currently the output of /sys/kernel/transparent_hugepage/hugepages-xxxkB is always inherit madvise [never] But no strong opinion on this. > static ssize_t enabled_store(struct kobject *kobj, > struct kobj_attribute *attr, > const char *buf, size_t count) >@@ -515,48 +529,54 @@ static ssize_t anon_enabled_show(struct kobject *kobj, > return sysfs_emit(buf, "%s\n", output); > } > >+static bool set_anon_enabled_mode(int order, enum anon_enabled_mode mode) >+{ >+ static unsigned long *enabled_orders[] = { >+ &huge_anon_orders_always, >+ &huge_anon_orders_madvise, >+ &huge_anon_orders_inherit, >+ }; >+ enum anon_enabled_mode m; >+ bool changed = false; >+ >+ spin_lock(&huge_anon_orders_lock); >+ for (m = 0; m < ARRAY_SIZE(enabled_orders); m++) { >+ if (m == mode) >+ changed |= !__test_and_set_bit(order, enabled_orders[m]); >+ else >+ changed |= __test_and_clear_bit(order, enabled_orders[m]); >+ } >+ spin_unlock(&huge_anon_orders_lock); >+ >+ return changed; >+} >+ Nice cleanup, so Reviewed-by: Wei Yang > static ssize_t anon_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; >+ int mode; > >- if (sysfs_streq(buf, "always")) { >- spin_lock(&huge_anon_orders_lock); >- clear_bit(order, &huge_anon_orders_inherit); >- clear_bit(order, &huge_anon_orders_madvise); >- set_bit(order, &huge_anon_orders_always); >- spin_unlock(&huge_anon_orders_lock); >- } else if (sysfs_streq(buf, "inherit")) { >- spin_lock(&huge_anon_orders_lock); >- clear_bit(order, &huge_anon_orders_always); >- clear_bit(order, &huge_anon_orders_madvise); >- set_bit(order, &huge_anon_orders_inherit); >- spin_unlock(&huge_anon_orders_lock); >- } else if (sysfs_streq(buf, "madvise")) { >- spin_lock(&huge_anon_orders_lock); >- clear_bit(order, &huge_anon_orders_always); >- clear_bit(order, &huge_anon_orders_inherit); >- set_bit(order, &huge_anon_orders_madvise); >- spin_unlock(&huge_anon_orders_lock); >- } else if (sysfs_streq(buf, "never")) { >- spin_lock(&huge_anon_orders_lock); >- clear_bit(order, &huge_anon_orders_always); >- clear_bit(order, &huge_anon_orders_inherit); >- clear_bit(order, &huge_anon_orders_madvise); >- spin_unlock(&huge_anon_orders_lock); >- } else >- ret = -EINVAL; >+ mode = sysfs_match_string(anon_enabled_mode_strings, buf); >+ if (mode < 0) >+ return -EINVAL; > >- if (ret > 0) { >- int err; >+ if (set_anon_enabled_mode(order, mode)) { >+ int err = start_stop_khugepaged(); > >- 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 anon_enabled_attr = > >-- >2.52.0 > -- Wei Yang Help you, Help me