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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, 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> 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> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 8B05240011 X-Stat-Signature: jpdocogxsq1g4cn9fcofm4yhrob965km X-Rspam-User: X-HE-Tag: 1773767722-21062 X-HE-Meta: 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 M9wqvew2 g4BbzBrAhu5mFQswkYhYmdjiRE2JaTaenn5TuSXh59iFXTvMwq/iHBlrHQJy/6loronBGf65cCvFo3CsvXq7BlQdrA9W/gyib6KbthlkBPdD/w9IP2asvVd5tXxhNk6DWec1Q4oOocjAnd4hscDO8WvxMCdIykQdy+96D3GhGYVBkutSE7nGqpfVAYSHIIi1HDea+Hx0ry8nE8uG8g+2cHK43s1EuhFqn10UK4p2/hkc8Wam19iMDn6GPd+7N4X+n3OluFCuWjGLAB3Esukw5yYuK1fga9oH5lhVyzZMOkA04/V7JQ2soggqsHyt8rTdSYvnMhEUVeUl82Tr4UNZ44XtrAAyOToTxE75h4aL+SRTzr39X/BSuCzaLu8eNIvkKasDuX0qVY4YUT3rm4JhL6CF91L+8lXJoRpAfAwp7v6BgjdgEwPXtr6ZBRKkP5eFs/Ht9 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 >