From nobody Thu Dec 25 18:04:21 2025 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 07BF9C132 for ; Mon, 15 Jan 2024 08:20:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-d85ff70000001748-95-65a4eab45f59 From: Byungchul Park To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: kernel_team@skhynix.com, akpm@linux-foundation.org, ying.huang@intel.com, namit@vmware.com, vernhao@tencent.com, mgorman@techsingularity.net, hughd@google.com, willy@infradead.org, david@redhat.com, peterz@infradead.org, luto@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, rjgolo@gmail.com Subject: [PATCH v6 7/7] mm: Pause migrc mechanism at high memory pressure Date: Mon, 15 Jan 2024 17:19:53 +0900 Message-Id: <20240115081953.2521-8-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20240115081953.2521-1-byungchul@sk.com> References: <20240115081953.2521-1-byungchul@sk.com> X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFvrILMWRmVeSWpSXmKPExsXC9ZZnoe6WV0tSDV5cVbeYs34Nm8XnDf/Y LF5saGe0+Lr+F7PF0099LBaXd81hs7i35j+rxflda1ktdizdx2Rx6cACJovrux4yWhzvPcBk Mf/eZzaLzZumMlscnzKV0eL3D6COk7MmszgIenxv7WPx2DnrLrvHgk2lHptXaHks3vOSyWPT qk42j02fJrF7vDt3jt3jxIzfLB7zTgZ6vN93lc1j6y87j8ap19g8Pm+S83g3/y1bAH8Ul01K ak5mWWqRvl0CV8b5NZOZC24oVzxu3cjawNgh28XIySEhYCIxrWkJK4zd0HKLGcRmE1CXuHHj J5gtImAmcbD1D3sXIxcHs8BHJonV3ztYQBLCAp4SPQu3MoLYLAKqEhPetIHFeYEGzfzyngli qLzE6g0HwAZxCphKvPt4nB3EFgKqabm7jhVkqIRAM7vE0vP9bBANkhIHV9xgmcDIu4CRYRWj UGZeWW5iZo6JXkZlXmaFXnJ+7iZGYEQsq/0TvYPx04XgQ4wCHIxKPLw//i5OFWJNLCuuzD3E KMHBrCTCW31nSaoQb0piZVVqUX58UWlOavEhRmkOFiVxXqNv5SlCAumJJanZqakFqUUwWSYO TqkGRs+pWc4KGU5aTx5lljxscJr4MEDDk9V/VXL8lfwTG5doHPjBdmv3Ydu5DFc5mlWORsfz PZv1OpO1QnHh19VXXTtm+6RH3N7rcOKCU5qP3mu30y9XWW47fKjctHNdquGKbeLdWy6+bd/Q 9dlnxtW7qx7q9ezsnVYwI7LA3PCJltDDrlWJD1yUHiuxFGckGmoxFxUnAgAEz+8chAIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrBLMWRmVeSWpSXmKPExsXC5WfdrLvl1ZJUg+5NUhZz1q9hs/i84R+b xYsN7YwWX9f/YrZ4+qmPxeLw3JOsFpd3zWGzuLfmP6vF+V1rWS12LN3HZHHpwAImi+u7HjJa HO89wGQx/95nNovNm6YyWxyfMpXR4vcPoI6TsyazOAh5fG/tY/HYOesuu8eCTaUem1doeSze 85LJY9OqTjaPTZ8msXu8O3eO3ePEjN8sHvNOBnq833eVzWPxiw9MHlt/2Xk0Tr3G5vF5k5zH u/lv2QIEorhsUlJzMstSi/TtErgyzq+ZzFxwQ7nicetG1gbGDtkuRk4OCQETiYaWW8wgNpuA usSNGz/BbBEBM4mDrX/Yuxi5OJgFPjJJrP7ewQKSEBbwlOhZuJURxGYRUJWY8KYNLM4LNGjm l/dMEEPlJVZvOAA2iFPAVOLdx+PsILYQUE3L3XWsExi5FjAyrGIUycwry03MzDHVK87OqMzL rNBLzs/dxAgM72W1fybuYPxy2f0QowAHoxIP74+/i1OFWBPLiitzDzFKcDArifBW31mSKsSb klhZlVqUH19UmpNafIhRmoNFSZzXKzw1QUggPbEkNTs1tSC1CCbLxMEp1cC47ufENp675cE3 ReXfOTiEHTobu9Z2q05YxfvIsGfMtadztlRtuL9Kyv3IjYRiec5fnpJ/1tee75gS/efcq0lB cWomzS6HnwfwVwn7NqT4Tg5ZVfhycap6vpr7DNWtnheLf4Ztf768Yu/DgMVvBCZN5X2ozy5S +Cpe2+V2a9El873Sl/2PTexUYinOSDTUYi4qTgQA60wLeWsCAAA= X-CFilter-Loop: Reflected Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Regression was observed when the system is in high memory pressure with swap on, where migrc might keep a number of folios in its pending queue, which possibly makes it worse. So temporarily prevented migrc from working on that condition. Signed-off-by: Byungchul Park --- mm/internal.h | 20 ++++++++++++++++++++ mm/migrate.c | 18 +++++++++++++++++- mm/page_alloc.c | 13 +++++++++++++ 3 files changed, 50 insertions(+), 1 deletion(-) diff --git a/mm/internal.h b/mm/internal.h index 5b93e5abf953..7643ccb7c156 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -1285,6 +1285,8 @@ static inline void shrinker_debugfs_remove(struct den= try *debugfs_entry, #endif /* CONFIG_SHRINKER_DEBUG */ =20 #if defined(CONFIG_MIGRATION) && defined(CONFIG_ARCH_WANT_BATCHED_UNMAP_TL= B_FLUSH) +extern atomic_t migrc_pause_cnt; + /* * Reset the indicator indicating there are no writable mappings at the * beginning of every rmap traverse for unmap. Migrc can work only when @@ -1313,6 +1315,21 @@ static inline bool can_migrc_test(void) return current->can_migrc && current->tlb_ubc_ro.flush_required; } =20 +static inline void migrc_pause(void) +{ + atomic_inc(&migrc_pause_cnt); +} + +static inline void migrc_resume(void) +{ + atomic_dec(&migrc_pause_cnt); +} + +static inline bool migrc_paused(void) +{ + return !!atomic_read(&migrc_pause_cnt); +} + /* * Return the number of folios pending TLB flush that have yet to get * freed in the zone. @@ -1330,6 +1347,9 @@ bool migrc_flush_free_folios(void); static inline void can_migrc_init(void) {} static inline void can_migrc_fail(void) {} static inline bool can_migrc_test(void) { return false; } +static inline void migrc_pause(void) {} +static inline void migrc_resume(void) {} +static inline bool migrc_paused(void) { return false; } static inline int migrc_pending_nr_in_zone(struct zone *z) { return 0; } static inline bool migrc_flush_free_folios(void) { return false; } #endif diff --git a/mm/migrate.c b/mm/migrate.c index da4d43ac2622..b838f279f050 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -62,6 +62,12 @@ static struct tlbflush_unmap_batch migrc_ubc; static LIST_HEAD(migrc_folios); static DEFINE_SPINLOCK(migrc_lock); =20 +/* + * Increase on entry of handling high memory pressure e.g. direct + * reclaim, decrease on the exit. See __alloc_pages_slowpath(). + */ +atomic_t migrc_pause_cnt =3D ATOMIC_INIT(0); + static void init_tlb_ubc(struct tlbflush_unmap_batch *ubc) { arch_tlbbatch_clear(&ubc->arch); @@ -1922,7 +1928,8 @@ static int migrate_pages_batch(struct list_head *from, */ init_tlb_ubc(&pending_ubc); do_migrc =3D IS_ENABLED(CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH) && - (reason =3D=3D MR_DEMOTION || reason =3D=3D MR_NUMA_MISPLACED); + (reason =3D=3D MR_DEMOTION || reason =3D=3D MR_NUMA_MISPLACED) && + !migrc_paused(); =20 for (pass =3D 0; pass < nr_pass && retry; pass++) { retry =3D 0; @@ -1961,6 +1968,15 @@ static int migrate_pages_batch(struct list_head *fro= m, continue; } =20 + /* + * In case that the system is in high memory + * pressure, give up migrc mechanism this turn. + */ + if (unlikely(do_migrc && migrc_paused())) { + fold_ubc(tlb_ubc, &pending_ubc); + do_migrc =3D false; + } + can_migrc_init(); rc =3D migrate_folio_unmap(get_new_folio, put_new_folio, private, folio, &dst, mode, reason, diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6ef0c22b1109..366777afce7f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4072,6 +4072,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int o= rder, unsigned int cpuset_mems_cookie; unsigned int zonelist_iter_cookie; int reserve_flags; + bool migrc_paused =3D false; =20 restart: compaction_retries =3D 0; @@ -4203,6 +4204,16 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int = order, if (page) goto got_pg; =20 + /* + * The system is in very high memory pressure. Pause migrc from + * expanding its pending queue temporarily. + */ + if (!migrc_paused) { + migrc_pause(); + migrc_paused =3D true; + migrc_flush_free_folios(); + } + /* Caller is not willing to reclaim, we can't balance anything */ if (!can_direct_reclaim) goto nopage; @@ -4330,6 +4341,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int o= rder, warn_alloc(gfp_mask, ac->nodemask, "page allocation failure: order:%u", order); got_pg: + if (migrc_paused) + migrc_resume(); return page; } =20 --=20 2.17.1