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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vzciM-00000006AaX-0gpX; Mon, 09 Mar 2026 15:40:14 +0000 Date: Mon, 9 Mar 2026 15:40:13 +0000 From: Matthew Wilcox To: Xie Yuanbin Cc: rppt@kernel.org, david.laight.linux@gmail.com, akpm@linux-foundation.org, david@kernel.org, ljs@kernel.org, Liam.Howlett@oracle.com, vbabka@kernel.org, surenb@google.com, mhocko@suse.com, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, morbo@google.com, justinstitt@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH] mm: optimize the implementation of WARN_ON_ONCE_GFP() Message-ID: References: <20260309153811.40958-1-qq570070308@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260309153811.40958-1-qq570070308@gmail.com> X-Stat-Signature: h3nmiab1bsrgzjy6dtfcjomsrwzgzh83 X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: DE3F82000B X-HE-Tag: 1773070816-718588 X-HE-Meta: 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 wS0HuCtR QOF4650insmaB+zRmZoCcMBpcd0h1H8v1Fuis6+gtfkkuMMnhOPo1YCAlzC+SS0kMbPkgR5j6MxfSMyhmHH7pxo6ykaxfiSGN2nM4BDK+glQp2FobrwdbSUb826d7rQntdl/7S7B3+pd/w+ylP83GVXrA5yunuIshFnVbQBIxkHDICpAz7vadsx/66SkaIfCSepxeFx8pr/wqM2E9XPK1zd0eDIqr3F7Wou8bGCWdHbJpigk0u1CvRGCLd8kxmCk7cznz1htTNoTIOXW1LEhEpAoAyA72PRPR4Cz3T2AfEUGU7e8vLDXhMCGz9BQfEEwBzoh0N2KVqhpX+m2wAqSRdnWBvA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 09, 2026 at 11:38:11PM +0800, Xie Yuanbin wrote: > As shown in the commit message of commit 242b872239f6a7deacbc > ("include/linux/once_lite.h: fix judgment in WARN_ONCE with clang"), > the code "unlikely(a && b)" may generate poor assembly code if it is > actually "unlikely(a) && unlikely(b)" or "unlikely(a) && b". Why fix this in multiple places in the kernel instead of once in clang?