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Sun, 15 Feb 2026 02:25:35 -0800 (PST) From: Kairui Song Date: Sun, 15 Feb 2026 18:25:10 +0800 Subject: [PATCH 2/2] mm, swap: merge common convention and simplify allocation helper Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260215-hibernate-perf-v1-2-f55ee9ee67db@tencent.com> References: <20260215-hibernate-perf-v1-0-f55ee9ee67db@tencent.com> In-Reply-To: <20260215-hibernate-perf-v1-0-f55ee9ee67db@tencent.com> To: linux-mm@kvack.org Cc: Andrew Morton , Chris Li , Kemeng Shi , Nhat Pham , Baoquan He , Barry Song , "Rafael J. Wysocki" , Carsten Grohmann , linux-kernel@vger.kernel.org, "open list:SUSPEND TO RAM" , Kairui Song X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1771151125; l=2753; i=kasong@tencent.com; s=kasong-sign-tencent; h=from:subject:message-id; bh=+lKDO9BRU6kc51T9mv3KyI+WElk31bKrGwbPt/FiL4w=; b=mc8fhlhZndV1qntjOVtm5dnTc05MQRd1xhCwdQbwILalsMpHVxJCLtTKLY8kHpgNXluNOsPei GAN9PELyjVmC94zru8UxwPQxV9dNA8wexNL6GEtskSPCreFXRwSc4/4 X-Developer-Key: i=kasong@tencent.com; a=ed25519; pk=kCdoBuwrYph+KrkJnrr7Sm1pwwhGDdZKcKrqiK8Y1mI= From: Kairui Song almost all callers of the cluster scan helper require the: lock -> check usefulness/emptiness -> unlock routine. So merge them into the same helper to simplify the code. This should also improve the scan slightly, as a few callers didn't check the emptiness, which might help reduce fragmentation in rare cases. Signed-off-by: Kairui Song --- mm/swapfile.c | 30 ++++++++---------------------- 1 file changed, 8 insertions(+), 22 deletions(-) diff --git a/mm/swapfile.c b/mm/swapfile.c index bcac10d96fb5..03cc0ff4dc8c 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -923,11 +923,14 @@ static unsigned int alloc_swap_scan_cluster(struct sw= ap_info_struct *si, bool need_reclaim, ret, usable; =20 lockdep_assert_held(&ci->lock); - VM_WARN_ON(!cluster_is_usable(ci, order)); =20 - if (end < nr_pages || ci->count + nr_pages > SWAPFILE_CLUSTER) + if (!cluster_is_usable(ci, order) || end < nr_pages || + ci->count + nr_pages > SWAPFILE_CLUSTER) goto out; =20 + if (cluster_is_empty(ci)) + offset =3D cluster_offset(si, ci); + for (end -=3D nr_pages; offset <=3D end; offset +=3D nr_pages) { need_reclaim =3D false; if (!cluster_scan_range(si, ci, offset, nr_pages, &need_reclaim)) @@ -1060,14 +1063,7 @@ static unsigned long cluster_alloc_swap_entry(struct= swap_info_struct *si, goto new_cluster; =20 ci =3D swap_cluster_lock(si, offset); - /* Cluster could have been used by another order */ - if (cluster_is_usable(ci, order)) { - if (cluster_is_empty(ci)) - offset =3D cluster_offset(si, ci); - found =3D alloc_swap_scan_cluster(si, ci, folio, offset); - } else { - swap_cluster_unlock(ci); - } + found =3D alloc_swap_scan_cluster(si, ci, folio, offset); if (found) goto done; } @@ -1332,14 +1328,7 @@ static bool swap_alloc_fast(struct folio *folio) return false; =20 ci =3D swap_cluster_lock(si, offset); - if (cluster_is_usable(ci, order)) { - if (cluster_is_empty(ci)) - offset =3D cluster_offset(si, ci); - alloc_swap_scan_cluster(si, ci, folio, offset); - } else { - swap_cluster_unlock(ci); - } - + alloc_swap_scan_cluster(si, ci, folio, offset); put_swap_device(si); return folio_test_swapcache(folio); } @@ -1945,10 +1934,7 @@ swp_entry_t swap_alloc_hibernation_slot(int type) pcp_offset =3D this_cpu_read(percpu_swap_cluster.offset[0]); if (pcp_si =3D=3D si && pcp_offset) { ci =3D swap_cluster_lock(si, pcp_offset); - if (cluster_is_usable(ci, 0)) - offset =3D alloc_swap_scan_cluster(si, ci, NULL, pcp_offset); - else - swap_cluster_unlock(ci); + offset =3D alloc_swap_scan_cluster(si, ci, NULL, pcp_offset); } if (!offset) offset =3D cluster_alloc_swap_entry(si, NULL); --=20 2.52.0