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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2B25C48BF6 for ; Tue, 27 Feb 2024 03:03:15 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4265B4401E2; Mon, 26 Feb 2024 22:03:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3D5F644017F; Mon, 26 Feb 2024 22:03:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 29DE04401E2; Mon, 26 Feb 2024 22:03:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 17F3344017F for ; Mon, 26 Feb 2024 22:03:15 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id B31D980AB9 for ; Tue, 27 Feb 2024 03:03:14 +0000 (UTC) X-FDA: 81836087508.09.C8144FD Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) by imf13.hostedemail.com (Postfix) with ESMTP id E25162000D for ; Tue, 27 Feb 2024 03:03:11 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=bytedance.com (policy=quarantine); spf=pass (imf13.hostedemail.com: domain of chengming.zhou@linux.dev designates 95.215.58.188 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1709002992; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:in-reply-to: references; bh=vFjahJpGLwaJimtqnNwwI7hbGSJsE28xFDghmgPFIk0=; b=LtsjnmJSajEJnT6CBJwLRY+GKXjQzZnjdWiP8n/jdbXcXxKD8ghCurVqnFPuat3oHviZ29 MNSrwBc5psd6i9hIzt824nY7jexJ9jIj01aH7/CBal3nfCS50R6DATOpSVcvM74bt5csUV q0TxObv3NhyqHNADRJ3SiCaSJ0cte0s= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=none; dmarc=fail reason="SPF not aligned (relaxed), No valid DKIM" header.from=bytedance.com (policy=quarantine); spf=pass (imf13.hostedemail.com: domain of chengming.zhou@linux.dev designates 95.215.58.188 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1709002992; a=rsa-sha256; cv=none; b=z73nDdVxxgN+nQPCIPTQ5QV9LRuOATuW09ICDm5RrL1EBV6ATUedMBRMFi5TgfZFLh7EWd kFW+zJ3jS3CTZlSSUZ5Y37Xy8s0NJ/GiHz7JLTZtnDUN5aZ1JmK0F5JVyUQkKT0kv9ajcq MS8Q5YyvmaX/S8oZmlzbY18NanNe5qM= Subject: [PATCH 0/2] mm/zsmalloc: simplify synchronization between zs_page_migrate() and free_zspage() MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-b4-tracking: H4sIAN1Q3WUC/w2LQQqAMAzAviI9O5hlevA3Xa06mFNW9KDs7/aWEPKBSk2iMHcfVHmSprOYDH0HvF PZxKXFHNBj8IiTe/WgnE82uMhy5dtF5AFXP4Y1BrAzkoqLlQrv9pY759Z+pn8dvmoAAAA= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou Date: Tue, 27 Feb 2024 03:02:53 +0000 Message-Id: <20240226-zsmalloc-zspage-rcu-v1-0-456b0ef1a89d@bytedance.com> To: yosryahmed@google.com, Sergey Senozhatsky , hannes@cmpxchg.org, nphamcs@gmail.com, Andrew Morton , Minchan Kim Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Chengming Zhou X-Developer-Signature: v=1; a=ed25519-sha256; t=1709002985; l=1565; i=zhouchengming@bytedance.com; s=20240220; h=from:subject:message-id; bh=DY8u0TYto4aeAduUrtq135WGTjcoSdC+IXz6XRCNMTc=; b=WkUVQbxbtoRQXjW/10v7MndbdXFUoW/g0x8wWemSA1Gwtsdawmeta3E9eNGhjqqeVOXcN3Ftn 4pe7vXyGdJcDerKNnZ/kdZz3Htz0zixmuRPxEadnX5V6nFYGNoQSuBi X-Developer-Key: i=zhouchengming@bytedance.com; a=ed25519; pk=5+68Wfci+T30FoQos5RH+hfToF6SlC+S9LMPSPBFWuw= X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: E25162000D X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: m8mhdhekq4nz3aa7s38adt6exh7jpyup X-Rspamd-Pre-Result: action=add header; module=dmarc; Action set by DMARC X-Rspam: Yes X-HE-Tag: 1709002991-836064 X-HE-Meta: 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 SqDBUqjd iE3Lda7rTdP/MbiqKrS8tG6hreXBKoMlSZlyW3jVFFTs4L3VOCqg080PVeVylMbK9r6xFyGGmNISnUcsJw+DmTo+WBR2Od3sQ3mgA3k7Yb4LSns2sNs2wuC/eLonooRSWUKQfJ13L41Qr8qjz6EIhlhVs+PP7ygnIxI3a9yBjjqHGnITK0tfNeQ3smAOuUS9LDBS+NuhkcRGP8GdjMq2NGgaoYhzL+1hSfu2OIGqDOAPGia5eQGPJy6KTLKPqHGdEsapiG/bg6QH62fDOPLgxxbNgSEnovW6+TdMzATthLKR6rD8UJgqq0qbye9S/QnD6eHOAlmIS9w2ZKbucAAkVq6ps9VKI3TIVrCREVUNjNlMXCVL/NMHCFh/qdw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello, free_zspage() has to hold locks of all pages, since zs_page_migrate() path rely on this page lock to protect the race between zs_free() and it, so it can safely get zspage from page->private. But this way is not good and simple enough: 1. Since zs_free() couldn't be sleepable, it can only trylock pages, or has to kick_deferred_free() to defer that to a work. 2. Even in the worker context, async_free_zspage() can't simply lock all pages in lock_zspage(), it's still trylock because of the race between zs_free() and zs_page_migrate(). Please see the commit 2505a981114d ("zsmalloc: fix races between asynchronous zspage free and page migration") for details. Actually, all free_zspage() needs is to get zspage from page safely, we can use RCU to achieve it easily. Then free_zspage() don't need to hold locks of all pages, so don't need the deferred free mechanism at all. This patchset implements it and remove all of deferred free related code. Thanks for review and comments! Signed-off-by: Chengming Zhou --- Chengming Zhou (2): mm/zsmalloc: don't hold locks of all pages when free_zspage() mm/zsmalloc: remove the deferred free mechanism mm/zsmalloc.c | 206 ++++++++++++++++------------------------------------------ 1 file changed, 56 insertions(+), 150 deletions(-) --- base-commit: ccbd06e764bac9bbf6b4e91c700fe6dd28f08fb3 change-id: 20240226-zsmalloc-zspage-rcu-b2c12f054fb4 Best regards, -- Chengming Zhou