From nobody Thu Dec 25 18:04:45 2025 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A002379F9 for ; Mon, 15 Jan 2024 08:20:12 +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-d85ff70000001748-89-65a4eab45724 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 5/7] mm: Add APIs to free a folio directly to the buddy bypassing pcp Date: Mon, 15 Jan 2024 17:19:51 +0900 Message-Id: <20240115081953.2521-6-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+NgFnrPLMWRmVeSWpSXmKPExsXC9ZZnke6WV0tSDebPkrWYs34Nm8XnDf/Y LF5saGe0+Lr+F7PF0099LBaXd81hs7i35j+rxflda1ktdizdx2Rx6cACJovrux4yWhzvPcBk Mf/eZzaLzZumMlscnzKV0eL3D6COk7MmszgIenxv7WPx2DnrLrvHgk2lHptXaHks3vOSyWPT qk42j02fJrF7vDt3jt3jxIzfLB7zTgZ6vN93lc1j6y87j8ap19g8Pm+S83g3/y1bAH8Ul01K ak5mWWqRvl0CV0bHdbaCP1IVh4/vZm5g/CHaxcjJISFgIrHo02N2GHvDsR1MIDabgLrEjRs/ mUFsEQEziYOtf4BquDiYBT4ySaz+3sECkhAWiJD4c/ksWBGLgKpE5789bF2MHBy8QIOWnayH mCkvsXrDAbASTgFTiXcfj4PtEgIqabm7jhVkpoRAM7vE8v9rWSEaJCUOrrjBMoGRdwEjwypG ocy8stzEzBwTvYzKvMwKveT83E2MwGhYVvsnegfjpwvBhxgFOBiVeHh//F2cKsSaWFZcmXuI UYKDWUmEt/rOklQh3pTEyqrUovz4otKc1OJDjNIcLErivEbfylOEBNITS1KzU1MLUotgskwc nFINjE4zODo3GK5az23z2HHVzVXObm9F1jPF3+1zr/slsXj3tvwk8SVl06eFxX00F1BsyWry WlclvijK22yjxDZPb6YvPh0JfW6zBSNPhXDE3jhgWPJUnFE7r/L2YftoHnPV1XfX7LxpJfTm 75PUDy9ldvD+ruW79sRh6+IdmcJmZ4+crwlfyljzUImlOCPRUIu5qDgRAEaPGL6CAgAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrGLMWRmVeSWpSXmKPExsXC5WfdrLvl1ZJUg9ZmQYs569ewWXze8I/N 4sWGdkaLr+t/MVs8/dTHYnF47klWi8u75rBZ3Fvzn9Xi/K61rBY7lu5jsrh0YAGTxfVdDxkt jvceYLKYf+8zm8XmTVOZLY5Pmcpo8fsHUMfJWZNZHIQ8vrf2sXjsnHWX3WPBplKPzSu0PBbv ecnksWlVJ5vHpk+T2D3enTvH7nFixm8Wj3knAz3e77vK5rH4xQcmj62/7Dwap15j8/i8Sc7j 3fy3bAECUVw2Kak5mWWpRfp2CVwZHdfZCv5IVRw+vpu5gfGHaBcjJ4eEgInEhmM7mEBsNgF1 iRs3fjKD2CICZhIHW/+wdzFycTALfGSSWP29gwUkISwQIfHn8lmwIhYBVYnOf3vYuhg5OHiB Bi07WQ8xU15i9YYDYCWcAqYS7z4eZwexhYBKWu6uY53AyLWAkWEVo0hmXlluYmaOqV5xdkZl XmaFXnJ+7iZGYGgvq/0zcQfjl8vuhxgFOBiVeHh//F2cKsSaWFZcmXuIUYKDWUmEt/rOklQh 3pTEyqrUovz4otKc1OJDjNIcLErivF7hqQlCAumJJanZqakFqUUwWSYOTqkGRvX/9/84uPN9 eJAfK+R/+bb8Bbfsb9eaXhVMvvw3UlknWe7jkliWlntncvxVLkmfl1NY09grNDWU/WmJ7uUU J6WJPhpfz/S6HYsPaGeT2154+35Lt2PSgpyJa9dkeMn/9w1Otk7fMrtuM0/Ij3mRS3fMKnst YPzwS6dvt66K8+QTU5ZOXHi2TImlOCPRUIu5qDgRALgW8+dpAgAA 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" This is a preparation for migrc mechanism that frees folios at a better time later, rather than the moment migrating folios. The folios freed by migrc are too old to keep in pcp. Signed-off-by: Byungchul Park --- include/linux/mm.h | 23 +++++++++++++++++++++++ mm/internal.h | 1 + mm/page_alloc.c | 10 ++++++++++ mm/swap.c | 7 +++++++ 4 files changed, 41 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index da5219b48d52..fc0581cce3a7 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1284,6 +1284,7 @@ static inline struct folio *virt_to_folio(const void = *x) } =20 void __folio_put(struct folio *folio); +void __folio_put_small_nopcp(struct folio *folio); =20 void put_pages_list(struct list_head *pages); =20 @@ -1483,6 +1484,28 @@ static inline void folio_put(struct folio *folio) __folio_put(folio); } =20 +/** + * folio_put_small_nopcp - Decrement the reference count on a folio. + * @folio: The folio. + * + * This is only for a single page folio to release directly to the buddy + * allocator bypassing pcp. + * + * If the folio's reference count reaches zero, the memory will be + * released back to the page allocator and may be used by another + * allocation immediately. Do not access the memory or the struct folio + * after calling folio_put_small_nopcp() unless you can be sure that it + * wasn't the last reference. + * + * Context: May be called in process or interrupt context, but not in NMI + * context. May be called while holding a spinlock. + */ +static inline void folio_put_small_nopcp(struct folio *folio) +{ + if (folio_put_testzero(folio)) + __folio_put_small_nopcp(folio); +} + /** * folio_put_refs - Reduce the reference count on a folio. * @folio: The folio. diff --git a/mm/internal.h b/mm/internal.h index b880f1e78700..3be8fd5604e8 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -451,6 +451,7 @@ extern int user_min_free_kbytes; =20 extern void free_unref_page(struct page *page, unsigned int order); extern void free_unref_page_list(struct list_head *list); +extern void free_pages_nopcp(struct page *page, unsigned int order); =20 extern void zone_pcp_reset(struct zone *zone); extern void zone_pcp_disable(struct zone *zone); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 733732e7e0ba..21b8c8cd1673 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -565,6 +565,16 @@ static inline void free_the_page(struct page *page, un= signed int order) __free_pages_ok(page, order, FPI_NONE); } =20 +void free_pages_nopcp(struct page *page, unsigned int order) +{ + /* + * This function will be used in case that the pages are too + * cold to keep in pcp e.g. migrc mechanism. So it'd better + * release the pages to the tail. + */ + __free_pages_ok(page, order, FPI_TO_TAIL); +} + /* * Higher-order pages are called "compound pages". They are structured th= usly: * diff --git a/mm/swap.c b/mm/swap.c index cd8f0150ba3a..3f37496a1184 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -106,6 +106,13 @@ static void __folio_put_small(struct folio *folio) free_unref_page(&folio->page, 0); } =20 +void __folio_put_small_nopcp(struct folio *folio) +{ + __page_cache_release(folio); + mem_cgroup_uncharge(folio); + free_pages_nopcp(&folio->page, 0); +} + static void __folio_put_large(struct folio *folio) { /* --=20 2.17.1