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Thu, 22 Feb 2024 21:56:31 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:b194:4f71:568a:eeb0]) by smtp.gmail.com with ESMTPSA id x92-20020a17090a6c6500b00298d8804ba8sm557787pjj.46.2024.02.22.21.56.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Feb 2024 21:56:31 -0800 (PST) Date: Fri, 23 Feb 2024 14:56:26 +0900 From: Sergey Senozhatsky To: Chengming Zhou Cc: hannes@cmpxchg.org, Sergey Senozhatsky , Minchan Kim , Andrew Morton , nphamcs@gmail.com, yosryahmed@google.com, linux-mm@kvack.org, Chengming Zhou , linux-kernel@vger.kernel.org Subject: Re: [PATCH RESEND 2/3] mm/zsmalloc: remove migrate_write_lock_nested() Message-ID: <20240223055626.GV11472@google.com> References: <20240219-b4-szmalloc-migrate-v1-0-fc21039bed7b@linux.dev> <20240219-b4-szmalloc-migrate-v1-2-fc21039bed7b@linux.dev> 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=us-ascii Content-Disposition: inline In-Reply-To: <20240219-b4-szmalloc-migrate-v1-2-fc21039bed7b@linux.dev> On (24/02/20 11:36), Chengming Zhou wrote: > From: Chengming Zhou > > The migrate write lock is to protect the race between zspage migration > and zspage objects' map users. > > We only need to lock out the map users of src zspage, not dst zspage, > which is safe to map by users concurrently, since we only need to do > obj_malloc() from dst zspage. > > So we can remove the migrate_write_lock_nested() use case. > > As we are here, cleanup the __zs_compact() by moving putback_zspage() > outside of migrate_write_unlock since we hold pool lock, no malloc or > free users can come in. > > Signed-off-by: Chengming Zhou Reviewed-by: Sergey Senozhatsky