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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 v3 2/4] mm: huge_memory: refactor anon_enabled_store() with change_anon_orders() Message-Id: <20260308140530.9ab6d1445d0936467eab4aef@linux-foundation.org> In-Reply-To: <20260307-thp_logs-v3-2-a45d2c8f3685@debian.org> References: <20260307-thp_logs-v3-0-a45d2c8f3685@debian.org> <20260307-thp_logs-v3-2-a45d2c8f3685@debian.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Stat-Signature: 5uoqy71p4tcgrdg3js3wshgsgndjomye X-Rspamd-Queue-Id: 42D432000C X-Rspamd-Server: rspam03 X-HE-Tag: 1773003933-983451 X-HE-Meta: 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 GFRQQs0W 8pjMP9Nk2RwnflaO3APwk3+QR3dTmlUo9RsIEROvHyKXrcfBKfiEk5ZV7ruNFDoZ3/lU42ZVEEgAYvvussgjw8J2R67snElEP2dCooHPdHvfeaSTB1VehYuZGp7GTl66gJvyiIqXIubn6bBegRIWkWa5SIDzWKudN90ntw9Tzt/Vh97ZIj1WapgBZIAdxW5aOty6VISGxN1u5S5bJ7P8JksWG6i7+9ZUo+Udl74FfN3AADS/dCwClAmDujqwSXXJ12eQtnmc65Pag9rqnzJ1Bj7Zxrf+MgCeRspioBqqPb03FY9PwTtlp3IcWlsMNAwg8hkei Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 07 Mar 2026 08:08:06 -0800 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. > > ... Somme nitlets, feel free to ignore: > --- 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, > + ANON_ENABLED_MADVISE, > + ANON_ENABLED_INHERIT, > + ANON_ENABLED_NEVER, > +}; If we're feeling fancy we could use ANON_ENABLED_ALWAYS = 0, ... here, just to make it clear that we iterate over the enum values with an integer and we *require* those values. > +static bool change_anon_orders(int order, enum anon_enabled_mode mode) > +{ > + static unsigned long *orders[] = { > + &huge_anon_orders_always, > + &huge_anon_orders_madvise, > + &huge_anon_orders_inherit, > + }; > + bool changed = false; > + int i; enum anon_enabled_mode m; might be clearer here? > + > + spin_lock(&huge_anon_orders_lock); > + for (i = 0; i < ARRAY_SIZE(orders); i++) { > + if (i == mode) > + changed |= !test_and_set_bit(order, orders[i]); > + else > + changed |= test_and_clear_bit(order, orders[i]); > + } > + spin_unlock(&huge_anon_orders_lock); > + > + return changed; > +}