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Thu, 30 Jul 2026 05:24:13 -0700 (PDT) Received: from debian.lan ([155.117.85.23]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-38f9b72d243sm995698a91.10.2026.07.30.05.24.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jul 2026 05:24:12 -0700 (PDT) From: Xueyuan Chen To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, zhaonanzhe@xiaomi.com, baohua@kernel.org, hannes@cmpxchg.org, youngjun.park@lge.com, baolin.wang@linux.alibaba.com, hughd@google.com, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, baoquan.he@linux.dev, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, qi.zheng@linux.dev, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com Subject: [RFC PATCH v5 4/4] mm/shmem: split large folios only on -E2BIG Date: Thu, 30 Jul 2026 20:23:04 +0800 Message-ID: <20260730122304.2496440-5-xueyuan.chen21@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260730122304.2496440-1-xueyuan.chen21@gmail.com> References: <20260730122304.2496440-1-xueyuan.chen21@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit shmem_writeout() currently splits a large folio on every folio_alloc_swap() failure. With the refined return-value contract, only -E2BIG indicates that splitting might allow smaller folios to be swapped out. Enter the split fallback only for -E2BIG. For -ENOSPC and -ENOMEM, redirty and reactivate the folio as before. Suggested-by: Baolin Wang Reviewed-by: Baolin Wang Signed-off-by: Xueyuan Chen --- mm/shmem.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 6641823bed16..eff38bb33d8a 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1608,7 +1608,7 @@ int shmem_writeout(struct swap_io_ctx *ctx, struct folio *folio, struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); pgoff_t index; - int nr_pages; + int nr_pages, ret; bool split = false; if ((info->flags & SHMEM_F_LOCKED) || sbinfo->noswap) @@ -1689,7 +1689,8 @@ int shmem_writeout(struct swap_io_ctx *ctx, struct folio *folio, folio_mark_uptodate(folio); } - if (!folio_alloc_swap(folio)) { + ret = folio_alloc_swap(folio); + if (!ret) { bool first_swapped = shmem_recalc_inode(inode, 0, nr_pages); int error; @@ -1742,7 +1743,7 @@ int shmem_writeout(struct swap_io_ctx *ctx, struct folio *folio, swap_cache_del_folio(folio); goto redirty; } - if (nr_pages > 1) + if (nr_pages > 1 && ret == -E2BIG) goto try_split; redirty: folio_mark_dirty(folio); -- 2.47.3