From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792635417; b=CngquNEPA0g/eau4LclD5VkXqTUSoz/HtNEQx0mb6GE9LkKnLuTsaV/QdiNKf2LxLbpo fV4toR+zOIpY4JZiVnbDobwOUm4l9gyJHMtkGUZY9neR/1u4mGkbXetXoV5CuJFuUBM0J hce7VpzjYsiGKiWxxh1+Y/S3BXhdwlMz8G9u/MXtHMJc3FSvau80BKuIeR4E1vDyhr2jv dE+CVvJVI3Cx2xtW0rEinXxASJMb4R6EsTCNcOZGqnLzQmc+0b9tr+pzDlbpk/sJADsUU opQOqTdZoNlLmdNshXIPp55hcRHVL8Z1UvwkbosbfA/9i9TckZaWUYD3Z4+4KpflRIA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792635417; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=rZUWkJhgXWYqHAz+iW5GZpRmYts2Zgab7cpsTnrfsc8=; b=wQ17HC6MPyUE1pXWOcxB+D8BITgUtQ+5pMurm02+RCkuUCsjS+wdBKqQnqI8aUVvsfTb KCTafXLZCiuFgQJpjcRHuzBMcwpU+Zvgbz8Vwshb5WiMCIAprop/SSUhBkhd+rBF9VypY K6PNpl68+eyuxjAEWQPsxvvaxj8cJZBVKObZtfFTyM7U1AIb8d8pcRfaK5NFAe7DXDh3E opZyWTj/T5Jqq7XC2fs9N1frVI1UHSoY+UVfhJK7wp/1uiYLhlfwSfXZ2aM5Ul2DG+Yp+ fxgvqvWmtDcb+A7n0K6hqLP7Rf8fdWZkK0+L7ztTzZNn8Mc/VSGxKgXmJquG2hBI11w== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=K2d+WB3M; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 71A34606A319 for ; Thu, 22 Oct 2026 02:16:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=K2d+WB3M Received: by smtp.kernel.org (Postfix) with ESMTPSA id 17B2B1F000C1; Thu, 22 Oct 2026 02:16:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792635417; bh=rZUWkJhgXWYqHAz+iW5GZpRmYts2Zgab7cpsTnrfsc8=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=K2d+WB3M9dJNSsALYwALl4Uw8c4od48Up+eYya+vJlCT9WpIXHoSLwKMwcwQ1YmyD xJcYKRNIRc5KGMQbLAnuDhvD11Po4P7XZmW19g2FVEPkaXAZQwRDpQWWNLwQ6lb6Th 8fkKLqVE56ryNBmRuC6Hn8mIj7ZVkmXPlYalt1yYgwDuUKZT2jLpL5F+ld1h3+kYBV DnR7MTGQa6gqdY8w/vVYqksosYpcLxLyXH00pQF8vEehTtdTFH2NEgNeDraqJh0qAR 2u19i9pF5FOV4bVvzhJdMJABqPdnvi/PD+BJFHHWz3k+Ryne1kv+Mz7BK0PXaHIWO6 sw4ZM2RqBUkkA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH bpf-next 5/9] uprobes: Don't sleep on mmap_lock under dup_mmap_sem Reply-To: sashiko-reviews@lists.linux.dev To: "Alexei Starovoitov" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20261022015712.1297331-6-alexei.starovoitov@gmail.com> References: <20261022015712.1297331-1-alexei.starovoitov@gmail.com> <20261022015712.1297331-6-alexei.starovoitov@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Thu, 22 Oct 2026 02:16:56 +0000 X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > From: Alexei Starovoitov >=20 > register_for_each_vma() takes dup_mmap_sem for writing, collects mms that > map the file and takes mmap_lock of every mm. fork() takes dup_mmap_sem f= or > reading. When mmap_lock of one mm is busy every fork() in the system waits > for it: >=20 > A: mmap(MAP_POPULATE) -> mmap_read_lock(A) > tracer: percpu_down_write(&dup_mmap_sem), mmap_write_lock(A) sleeps > others: fork() -> percpu_down_read(&dup_mmap_sem) sleeps >=20 > Only trylock mmap_lock under dup_mmap_sem. Leave mms with busy mmap_lock = in > the list, drop dup_mmap_sem and then wait for them. >=20 > dup_mmap_sem makes sure that mm doesn't fork between build_map_info() and > [ ... ] >=20 > enable uprobe event 105 -> 205 201 -> 481 207 -> 784 > disable uprobe event 225 -> 294 354 -> 579 407 -> 893 >=20 > Signed-off-by: Alexei Starovoitov Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261022015712.1297= 331-1-alexei.starovoitov@gmail.com?part=3D5