From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4F806FF8875 for ; Thu, 30 Apr 2026 04:06:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=AjOwhtb3aLC8dXcF5fdBlXdpp4mSyr4Dq8lBNuOOORA=; b=0/KdgzkA/Voouvj37XB3kyOb+b ZJ1ZnPPOJOZp3loaIwxALlAgqKNrSkMTW0gnwTUdB1E7fhk3KdxeKZMO0cwNxkiuqb2S7tk94Y5iD d9Sx7QW7Ine4BdU6jUPeWhYSQs7Cdw7ZhRJ0ncsqRGbjocGYVJ5D5TSOwGuG3b7YOfdTnmSX8Y8K4 y3uTJIwhQYgrLvbW/4L3udd423UxEOqwlyX3BGvcHrn2VB29F6bYtsj6XeXrhephybdpvkFG2RNSy kkyDTrYk7/AoSYbuGaDpXvTzLfPYafMBfEVD051xCIT9nCvfVtm9bWZfIDIo/3iDMqpyT6eTOrrQX ENqrqGUw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wIIf7-00000004dPg-3EXF; Thu, 30 Apr 2026 04:06:05 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wIIf6-00000004dOQ-1SZe; Thu, 30 Apr 2026 04:06:04 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:MIME-Version :References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=AjOwhtb3aLC8dXcF5fdBlXdpp4mSyr4Dq8lBNuOOORA=; b=gbVNsHmfrp3dlnjUGbqZ5l8qiS ROaAwj/M+qCPklMStrP21+ynBPts0egtBU3vG3bBx4KbGWCr//7YmlnyiRfgWLPQLtUylBcdBJ9T4 gcsP/UBxqetm6r2p0uXfsiyGWi4k4juHiKCCAQ4uONz1PNpUW7FggJmNznthVmKu+MwSvB0Snbwtz 8DsUCuGRVaZ40T7AFxQn6Xi8laLNALkCZ/T839DfMYtOfvV2acymB8bgJ5PAgCdCaAAWcAi8ajS3G ZImC3+gqobX4QTo3tYV6PZos4A5aXSfX3mut/uZn+gpEXCogrUYWvnDuAc91W77irvP3VyCnGSZsy 7qFj8BSQ==; Received: from sea.source.kernel.org ([172.234.252.31]) by desiato.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1wIIeT-00000006afk-30ou; Thu, 30 Apr 2026 04:05:39 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 953E9417E4; Thu, 30 Apr 2026 04:05:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B00CC2BCC6; Thu, 30 Apr 2026 04:05:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777521914; bh=6MPYWPf1QbIXw7VCTkYtFV9yBQTJYYcQnuchAn2u66s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uJyCN/cPD0/zuU5TMG/FWh17eVTVcTCG22wyND+Ln22vdCzvScs+KeOLVG9RmOssZ jDw1d8PhCAGGbMI/IFgx4Z5EBNcmkVO03z+9/CJtVz3K4wxUxjDLHuhXQrygfZY0vj Mz9EPYWMtvXMUkv1GvrXcIXqYy7f2Nbz3f61nlophvJmqpD4ikN6UOlFyXJonZi3kU apK9iwjy49sl7fMM6lNjIBPwaa1bmY1pG/z4xtRWqVUh4kt9XKZhnZLwyhRWE61vDF fxzmTVdxergJndpikZIoTxLjBRYHAUamicyvLwT/yqUnIVLaZSAeOqCic0yYJ36c4O EWCGitvEei8LA== From: "Barry Song (Xiaomi)" To: akpm@linux-foundation.org, linux-mm@kvack.org, willy@infradead.org Cc: david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jack@suse.cz, pfalcato@suse.de, wanglian@kylinos.cn, chentao@kylinos.cn, lianux.mm@gmail.com, kunwu.chan@gmail.com, liyangouwen1@oppo.com, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, "Barry Song (Xiaomi)" Subject: [PATCH v2 4/5] mm: Don't retry page fault if folio is uptodate during swap-in Date: Thu, 30 Apr 2026 12:04:26 +0800 Message-Id: <20260430040427.4672-5-baohua@kernel.org> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20260430040427.4672-1-baohua@kernel.org> References: <20260430040427.4672-1-baohua@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260430_050528_898727_B2C9EDCC X-CRM114-Status: UNSURE ( 9.94 ) X-CRM114-Notice: Please train this message. X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org If we are waiting for long I/O to complete, it makes sense to avoid holding locks for too long. However, if the folio is uptodate, we are likely only waiting for a concurrent PTE update to finish. Retrying the entire page fault seems excessive. Signed-off-by: Barry Song (Xiaomi) --- mm/memory.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 0c740ca363cc..a2e4f2d87ec8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4949,6 +4949,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) } swapcache = folio; + /* + * If the folio is uptodate, we are likely only waiting for + * another concurrent PTE mapping to complete, which should + * be brief. No need to drop the lock and retry the fault. + */ + if (folio_test_uptodate(folio)) + vmf->flags &= ~FAULT_FLAG_ALLOW_RETRY; ret |= folio_lock_or_retry(folio, vmf); if (ret & VM_FAULT_RETRY) { if (fault_flag_allow_retry_first(vmf->flags) && -- 2.39.3 (Apple Git-146)