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[103.168.172.201]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7cad23b5f51sm661832085a.11.2025.05.05.21.20.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 May 2025 21:20:55 -0700 (PDT) Received: from phl-compute-03.internal (phl-compute-03.phl.internal [10.202.2.43]) by mailfauth.phl.internal (Postfix) with ESMTP id 891501200068; Tue, 6 May 2025 00:20:55 -0400 (EDT) Received: from phl-mailfrontend-01 ([10.202.2.162]) by phl-compute-03.internal (MEProxy); Tue, 06 May 2025 00:20:55 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddvkeeftddtucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggv pdfurfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpih gvnhhtshculddquddttddmnecujfgurhephffvvefufffkofgjfhgggfestdekredtredt tdenucfhrhhomhepuehoqhhunhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrih hlrdgtohhmqeenucggtffrrghtthgvrhhnpefghfffvefhhfdvgfejgfekvdelgfekgeev ueehlefhiedvgeffjefgteeugfehieenucffohhmrghinhepkhgvrhhnvghlrdhorhhgne cuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepsghoqhhu nhdomhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqieelvdeghedtieegqdduje ejkeehheehvddqsghoqhhunhdrfhgvnhhgpeepghhmrghilhdrtghomhesfhhigihmvgdr nhgrmhgvpdhnsggprhgtphhtthhopedufedpmhhouggvpehsmhhtphhouhhtpdhrtghpth htohepmhhinhhgoheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepphgvthgvrhiisehi nhhfrhgruggvrggurdhorhhgpdhrtghpthhtohepmhhinhhgohesrhgvughhrghtrdgtoh hmpdhrtghpthhtohepfihilhhlsehkvghrnhgvlhdrohhrghdprhgtphhtthhopegsohhq uhhnrdhfvghnghesghhmrghilhdrtghomhdprhgtphhtthhopehlohhnghhmrghnsehrvg guhhgrthdrtghomhdprhgtphhtthhopehnrghthhgrnheskhgvrhhnvghlrdhorhhgpdhr tghpthhtohepnhhitghkrdguvghsrghulhhnihgvrhhsodhlkhhmlhesghhmrghilhdrtg homhdprhgtphhtthhopehmohhrsghosehgohhoghhlvgdrtghomh X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 6 May 2025 00:20:55 -0400 (EDT) From: Boqun Feng To: Ingo Molnar , Peter Zijlstra Cc: Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Andy Shevchenko Subject: [PATCH 1/3] lockdep: Move hlock_equal() to the respective ifdeffery Date: Mon, 5 May 2025 21:20:47 -0700 Message-Id: <20250506042049.50060-2-boqun.feng@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250506042049.50060-1-boqun.feng@gmail.com> References: <20250506042049.50060-1-boqun.feng@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: quoted-printable Content-Type: text/plain; charset="utf-8" From: Andy Shevchenko When hlock_equal() is unused, it prevents kernel builds with clang, `make W=3D1` and CONFIG_WERROR=3Dy, CONFIG_LOCKDEP=3Dy and CONFIG_LOCKDEP_SMALL=3Dn: lockdep.c:2005:20: error: unused function 'hlock_equal' [-Werror,-Wunused= -function] Fix this by moving the function to the respective existing ifdeffery for its the only user. See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static inline functions for W=3D1 build"). Fixes: 68e305678583 ("lockdep: Adjust check_redundant() for recursive read = change") Signed-off-by: Andy Shevchenko Signed-off-by: Boqun Feng Link: https://lore.kernel.org/r/20250415085857.495543-1-andriy.shevchenko@l= inux.intel.com --- kernel/locking/lockdep.c | 70 ++++++++++++++++++++-------------------- 1 file changed, 35 insertions(+), 35 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index b15757e63626..ff2ce90a87bc 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1976,41 +1976,6 @@ print_circular_bug_header(struct lock_list *entry, u= nsigned int depth, print_circular_bug_entry(entry, depth); } =20 -/* - * We are about to add A -> B into the dependency graph, and in __bfs() a - * strong dependency path A -> .. -> B is found: hlock_class equals - * entry->class. - * - * If A -> .. -> B can replace A -> B in any __bfs() search (means the for= mer - * is _stronger_ than or equal to the latter), we consider A -> B as redun= dant. - * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), a= nd A - * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the - * dependency graph, as any strong path ..-> A -> B ->.. we can get with - * having dependency A -> B, we could already get a equivalent path ..-> A= -> - * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant. - * - * We need to make sure both the start and the end of A -> .. -> B is not - * weaker than A -> B. For the start part, please see the comment in - * check_redundant(). For the end part, we need: - * - * Either - * - * a) A -> B is -(*R)-> (everything is not weaker than that) - * - * or - * - * b) A -> .. -> B is -(*N)-> (nothing is stronger than this) - * - */ -static inline bool hlock_equal(struct lock_list *entry, void *data) -{ - struct held_lock *hlock =3D (struct held_lock *)data; - - return hlock_class(hlock) =3D=3D entry->class && /* Found A -> .. -> B */ - (hlock->read =3D=3D 2 || /* A -> B is -(*R)-> */ - !entry->only_xr); /* A -> .. -> B is -(*N)-> */ -} - /* * We are about to add B -> A into the dependency graph, and in __bfs() a * strong dependency path A -> .. -> B is found: hlock_class equals @@ -2915,6 +2880,41 @@ static inline bool usage_skip(struct lock_list *entr= y, void *mask) #endif /* CONFIG_TRACE_IRQFLAGS */ =20 #ifdef CONFIG_LOCKDEP_SMALL +/* + * We are about to add A -> B into the dependency graph, and in __bfs() a + * strong dependency path A -> .. -> B is found: hlock_class equals + * entry->class. + * + * If A -> .. -> B can replace A -> B in any __bfs() search (means the for= mer + * is _stronger_ than or equal to the latter), we consider A -> B as redun= dant. + * For example if A -> .. -> B is -(EN)-> (i.e. A -(E*)-> .. -(*N)-> B), a= nd A + * -> B is -(ER)-> or -(EN)->, then we don't need to add A -> B into the + * dependency graph, as any strong path ..-> A -> B ->.. we can get with + * having dependency A -> B, we could already get a equivalent path ..-> A= -> + * .. -> B -> .. with A -> .. -> B. Therefore A -> B is redundant. + * + * We need to make sure both the start and the end of A -> .. -> B is not + * weaker than A -> B. For the start part, please see the comment in + * check_redundant(). For the end part, we need: + * + * Either + * + * a) A -> B is -(*R)-> (everything is not weaker than that) + * + * or + * + * b) A -> .. -> B is -(*N)-> (nothing is stronger than this) + * + */ +static inline bool hlock_equal(struct lock_list *entry, void *data) +{ + struct held_lock *hlock =3D (struct held_lock *)data; + + return hlock_class(hlock) =3D=3D entry->class && /* Found A -> .. -> B */ + (hlock->read =3D=3D 2 || /* A -> B is -(*R)-> */ + !entry->only_xr); /* A -> .. -> B is -(*N)-> */ +} + /* * Check that the dependency graph starting at can lead to * or not. 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[103.168.172.201]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7cad2441633sm655256585a.107.2025.05.05.21.20.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 May 2025 21:20:57 -0700 (PDT) Received: from phl-compute-04.internal (phl-compute-04.phl.internal [10.202.2.44]) by mailfauth.phl.internal (Postfix) with ESMTP id 053211200068; Tue, 6 May 2025 00:20:57 -0400 (EDT) Received: from phl-mailfrontend-01 ([10.202.2.162]) by phl-compute-04.internal (MEProxy); Tue, 06 May 2025 00:20:57 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddvkeeftddtucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggv pdfurfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpih gvnhhtshculddquddttddmnecujfgurhephffvvefufffkofgjfhgggfestdekredtredt tdenucfhrhhomhepuehoqhhunhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrih hlrdgtohhmqeenucggtffrrghtthgvrhhnpefghfffvefhhfdvgfejgfekvdelgfekgeev ueehlefhiedvgeffjefgteeugfehieenucffohhmrghinhepkhgvrhhnvghlrdhorhhgne cuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepsghoqhhu nhdomhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqieelvdeghedtieegqdduje ejkeehheehvddqsghoqhhunhdrfhgvnhhgpeepghhmrghilhdrtghomhesfhhigihmvgdr nhgrmhgvpdhnsggprhgtphhtthhopeduvddpmhhouggvpehsmhhtphhouhhtpdhrtghpth htohepmhhinhhgoheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepphgvthgvrhiisehi nhhfrhgruggvrggurdhorhhgpdhrtghpthhtohepmhhinhhgohesrhgvughhrghtrdgtoh hmpdhrtghpthhtohepfihilhhlsehkvghrnhgvlhdrohhrghdprhgtphhtthhopegsohhq uhhnrdhfvghnghesghhmrghilhdrtghomhdprhgtphhtthhopehlohhnghhmrghnsehrvg guhhgrthdrtghomhdprhgtphhtthhopehnrghthhgrnheskhgvrhhnvghlrdhorhhgpdhr tghpthhtohepnhhitghkrdguvghsrghulhhnihgvrhhsodhlkhhmlhesghhmrghilhdrtg homhdprhgtphhtthhopehmohhrsghosehgohhoghhlvgdrtghomh X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 6 May 2025 00:20:56 -0400 (EDT) From: Boqun Feng To: Ingo Molnar , Peter Zijlstra Cc: Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH 2/3] locking/lockdep: Prevent abuse of lockdep subclass Date: Mon, 5 May 2025 21:20:48 -0700 Message-Id: <20250506042049.50060-3-boqun.feng@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250506042049.50060-1-boqun.feng@gmail.com> References: <20250506042049.50060-1-boqun.feng@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: quoted-printable Content-Type: text/plain; charset="utf-8" From: Waiman Long To catch the code trying to use a subclass value >=3D MAX_LOCKDEP_SUBCLASSES (8), add a DEBUG_LOCKS_WARN_ON() statement to notify the users that such a large value is not allowed. [boqun: Reword the commit log with a more objective tone] Signed-off-by: Waiman Long Signed-off-by: Boqun Feng Link: https://lore.kernel.org/r/20250409143751.2010391-1-longman@redhat.com --- kernel/locking/lockdep.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index ff2ce90a87bc..58883c8375d1 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -5101,6 +5101,9 @@ static int __lock_acquire(struct lockdep_map *lock, u= nsigned int subclass, lockevent_inc(lockdep_nocheck); } =20 + if (DEBUG_LOCKS_WARN_ON(subclass >=3D MAX_LOCKDEP_SUBCLASSES)) + return 0; + if (subclass < NR_LOCKDEP_CACHING_CLASSES) class =3D lock->class_cache[subclass]; /* --=20 2.39.5 (Apple Git-154) From nobody Tue Dec 16 17:15:09 2025 Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B60A290DA3 for ; Tue, 6 May 2025 04:21:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.169 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746505262; cv=none; b=JK/8/usEHMxtENT22CbwnURtbLYfnkO9/Y5yF1DejnOEXaWbTCOuckDgubqxNqnktahuvRkpx8tDY0Jtlk5AfbdpPtk2d/KtOo0EItbhI0PWuXyn+rfAlUAK2wtiVNM6Hla28+RbgKsZFeM/vEEocD9Y5iwXzpZtMoFJy/ePt6I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746505262; c=relaxed/simple; bh=DNwVyTCcOjrl4kbNqvDRwjBggTFRm5nqgPRq9w9xVEA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Dsf71Otr2nVGdGOnKBeKs9RMi7A6ccBgTJMdIYHuxrpakixeF4OXoUvG6oagYxB1VcHTU9UocvBpScSP/ABxGqkM+5xqHRd5+pJVTd9H4WR1dOX8PkrYTVwfIWH986uqv2jy1lUJkfB6pa1UpyhqA6/Px0QW545JsnfGXoba0lI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=fvQnlIm9; arc=none smtp.client-ip=209.85.160.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fvQnlIm9" Received: by mail-qt1-f169.google.com with SMTP id d75a77b69052e-47690a4ec97so65817941cf.2 for ; Mon, 05 May 2025 21:21:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1746505259; x=1747110059; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:feedback-id:from:to:cc:subject :date:message-id:reply-to; bh=3OUeV+ysAiL6au/JA8NItOuHiGPdhnma0mnX2ERy5dE=; b=fvQnlIm9c6VFvjZf6rfL8S85rROt9HjKYHNoQM1IAAAj1l4SOwPdx9YmOtMIStuzFZ 9+MYQ7CBnTusUoa85hhgGAjTsvAyqjlSkrTcwySoneQm3wCUNzR9Whrx8U9iL8kfPGNP 5tDXV46+a7Epe1Sqe9FGZKie19aNfqUTQawsd/ONPBRlA6OZcg1j0Bgytu1DR92bEnAw Ci4/z6CoqO/C8f1esHGw8gDiWrqxwvGN5Y9FR9F0azj+R31jyQwK3yqA/ih5zI/nCuGn 9n9W5+vr2v9k6acmkhUXdQDoh1vMfb6oF8l17p4bepK3xfIzfqIQzHn1posLApRqH57T n9FQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1746505259; x=1747110059; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:feedback-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=3OUeV+ysAiL6au/JA8NItOuHiGPdhnma0mnX2ERy5dE=; b=KuSRhhFgS3ddoaaPDPRR7xNTwMidVfQhQdpdqyQpViH8CNW/cSXnSP+OmgwyqQhozg dLkBfjh3Pafz1FGFg0WzHtR9IvzpwTOGmthICJvgEoHzL0IfVeUKSQHQ7Hm49y3/K/o8 cURKT4AqI1BTy34nVL/HtzyuHvwogASlUkEaMYpenxOjr+zkRBbb0IlPr2a6qEKsNgFx af3128aEJROf1CC1hGFMDdhZucczW4MiiDBeYqnSuWr/01rVVdrAAwd8c/ictSLC/wm9 UN2e3XrToV6DwlkwIEWzqiaeHPhzRdCuym5Jl8UQ7ajrjFd7QEElyRWhcZhWs+gxm4OR duyw== X-Forwarded-Encrypted: i=1; AJvYcCVoDHK3rF9ruvafUD+PxEgvKM2DkLExqZJ0yo/cw7mkToslJA2KMNWJ1Er4Mm+TjooNO8EtTDiLUf60Cvw=@vger.kernel.org X-Gm-Message-State: AOJu0YyEQY8/UKJJgneNjTJ/Jr2L7TdRJ60bm1wp92YxJvs03sEx7f4H neeeFD6K16btfoIUsdXLxDyKJEXyP4zBTsrovyU1Wl6N9zENkmgt X-Gm-Gg: ASbGncvIxD4kmb+r5hjGEFR7Ow6cw7NW6IP/bk5cpOUQgNfoCoh7RR4jScJe0L7as8j QYtiEVi6dpejdviPtnPF8oOuzhmufpfdm6hBIw/lD6gS9XO0j8pHnJysD2VBwHglSezbiysG60n BQJ+pfDDaUp3e0C2VhQh2BV5mMGlZGMeIRSkJkDbT0WSOV5m/ycvVNvp4koZq9/ExACUlYYUTJv dCSk+rs/whzA08JI29kUJIgc4kJTxqu6BqCeiepGEPc3QJMR267Cj3m0LI9evmBCZXPu5O/b8iM d9V07RVYVVSluavn9eQU+z5Jaf2jn/xKRqRdjDaRxQJNVp1yUQxwLsxHQa6DKB3luQbJsicGkaQ 6DdsRYLTsENO7WhyjqLm3osbAAXt6oyE= X-Google-Smtp-Source: AGHT+IH+kp9foAY4t6M00GAm1xmuSa34/5hEqfuNRr7JNPk7Jcnx40ELv8vv/dVN+mrv6oEHsbe73w== X-Received: by 2002:a05:6214:b6e:b0:6f4:d60d:dd29 with SMTP id 6a1803df08f44-6f5157301d3mr260126456d6.5.1746505259319; Mon, 05 May 2025 21:20:59 -0700 (PDT) Received: from fauth-a2-smtp.messagingengine.com (fauth-a2-smtp.messagingengine.com. [103.168.172.201]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6f50f44f5a2sm64779936d6.78.2025.05.05.21.20.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 May 2025 21:20:58 -0700 (PDT) Received: from phl-compute-08.internal (phl-compute-08.phl.internal [10.202.2.48]) by mailfauth.phl.internal (Postfix) with ESMTP id 7F2881200068; Tue, 6 May 2025 00:20:58 -0400 (EDT) Received: from phl-mailfrontend-01 ([10.202.2.162]) by phl-compute-08.internal (MEProxy); Tue, 06 May 2025 00:20:58 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddvkeeftdduucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggv pdfurfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpih gvnhhtshculddquddttddmnecujfgurhephffvvefufffkofgjfhgggfestdekredtredt tdenucfhrhhomhepuehoqhhunhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrih hlrdgtohhmqeenucggtffrrghtthgvrhhnpefghfffvefhhfdvgfejgfekvdelgfekgeev ueehlefhiedvgeffjefgteeugfehieenucffohhmrghinhepkhgvrhhnvghlrdhorhhgne cuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepsghoqhhu nhdomhgvshhmthhprghuthhhphgvrhhsohhnrghlihhthidqieelvdeghedtieegqdduje ejkeehheehvddqsghoqhhunhdrfhgvnhhgpeepghhmrghilhdrtghomhesfhhigihmvgdr nhgrmhgvpdhnsggprhgtphhtthhopeduvddpmhhouggvpehsmhhtphhouhhtpdhrtghpth htohepmhhinhhgoheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepphgvthgvrhiisehi nhhfrhgruggvrggurdhorhhgpdhrtghpthhtohepmhhinhhgohesrhgvughhrghtrdgtoh hmpdhrtghpthhtohepfihilhhlsehkvghrnhgvlhdrohhrghdprhgtphhtthhopegsohhq uhhnrdhfvghnghesghhmrghilhdrtghomhdprhgtphhtthhopehlohhnghhmrghnsehrvg guhhgrthdrtghomhdprhgtphhtthhopehnrghthhgrnheskhgvrhhnvghlrdhorhhgpdhr tghpthhtohepnhhitghkrdguvghsrghulhhnihgvrhhsodhlkhhmlhesghhmrghilhdrtg homhdprhgtphhtthhopehmohhrsghosehgohhoghhlvgdrtghomh X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 6 May 2025 00:20:57 -0400 (EDT) From: Boqun Feng To: Ingo Molnar , Peter Zijlstra Cc: Ingo Molnar , Will Deacon , Boqun Feng , Waiman Long , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH 3/3] locking/lockdep: Add # of dynamic keys stat to /proc/lockdep_stats Date: Mon, 5 May 2025 21:20:49 -0700 Message-Id: <20250506042049.50060-4-boqun.feng@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20250506042049.50060-1-boqun.feng@gmail.com> References: <20250506042049.50060-1-boqun.feng@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: quoted-printable Content-Type: text/plain; charset="utf-8" From: Waiman Long There have been recent reports about running out of lockdep keys (MAX_LOCKDEP_KEYS too low!). One possible reason is that too many dynamic keys have been registered. A possible culprit is the lockdep_register_key() call in qdisc_alloc() of net/sched/sch_generic.c. Currently, there is no way to find out how many dynamic keys have been registered. Add such a stat to the /proc/lockdep_stats to get better clarity. Signed-off-by: Waiman Long Signed-off-by: Boqun Feng Link: https://lore.kernel.org/r/20250425001155.775458-1-longman@redhat.com --- kernel/locking/lockdep.c | 3 +++ kernel/locking/lockdep_internals.h | 1 + kernel/locking/lockdep_proc.c | 2 ++ 3 files changed, 6 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 58883c8375d1..e7166ff64681 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -219,6 +219,7 @@ static DECLARE_BITMAP(list_entries_in_use, MAX_LOCKDEP_= ENTRIES); static struct hlist_head lock_keys_hash[KEYHASH_SIZE]; unsigned long nr_lock_classes; unsigned long nr_zapped_classes; +unsigned long nr_dynamic_keys; unsigned long max_lock_class_idx; struct lock_class lock_classes[MAX_LOCKDEP_KEYS]; DECLARE_BITMAP(lock_classes_in_use, MAX_LOCKDEP_KEYS); @@ -1238,6 +1239,7 @@ void lockdep_register_key(struct lock_class_key *key) goto out_unlock; } hlist_add_head_rcu(&key->hash_entry, hash_head); + nr_dynamic_keys++; out_unlock: graph_unlock(); restore_irqs: @@ -6606,6 +6608,7 @@ void lockdep_unregister_key(struct lock_class_key *ke= y) pf =3D get_pending_free(); __lockdep_free_key_range(pf, key, 1); need_callback =3D prepare_call_rcu_zapped(pf); + nr_dynamic_keys--; } lockdep_unlock(); raw_local_irq_restore(flags); diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_in= ternals.h index 20f9ef58d3d0..82156caf77d1 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -138,6 +138,7 @@ extern unsigned long nr_lock_classes; extern unsigned long nr_zapped_classes; extern unsigned long nr_zapped_lock_chains; extern unsigned long nr_list_entries; +extern unsigned long nr_dynamic_keys; long lockdep_next_lockchain(long i); unsigned long lock_chain_count(void); extern unsigned long nr_stack_trace_entries; diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c index 6db0f43fc4df..b52c07c4707c 100644 --- a/kernel/locking/lockdep_proc.c +++ b/kernel/locking/lockdep_proc.c @@ -286,6 +286,8 @@ static int lockdep_stats_show(struct seq_file *m, void = *v) #endif seq_printf(m, " lock-classes: %11lu [max: %lu]\n", nr_lock_classes, MAX_LOCKDEP_KEYS); + seq_printf(m, " dynamic-keys: %11lu\n", + nr_dynamic_keys); seq_printf(m, " direct dependencies: %11lu [max: %lu]\n", nr_list_entries, MAX_LOCKDEP_ENTRIES); seq_printf(m, " indirect dependencies: %11lu\n", --=20 2.39.5 (Apple Git-154)