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 AF1AECEFC24 for ; Tue, 8 Oct 2024 15:21:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 11FE46B008C; Tue, 8 Oct 2024 11:21:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0D07C6B0092; Tue, 8 Oct 2024 11:21:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EB2BC6B0093; Tue, 8 Oct 2024 11:21:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id C59C56B008C for ; Tue, 8 Oct 2024 11:21:26 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 467EF1A051F for ; Tue, 8 Oct 2024 15:21:24 +0000 (UTC) X-FDA: 82650798972.01.0ABC9DF Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf15.hostedemail.com (Postfix) with ESMTP id 5A0F3A0004 for ; Tue, 8 Oct 2024 15:21:24 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=iAqaFm1a; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf15.hostedemail.com: domain of oleg@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=oleg@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1728400735; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=ruYSLgW7gfmln5kN4ADH0+uUUeJjmQiMQYi2GHJLhGM=; b=jLQhjhtrzwj5frsuIg3LwFwABbbvfDndIwg6GnsYjrJDrSQSVFBlBbNkTB6AEjdEHue254 0wBuwuSzPVjevMKuYjguHIE8Ooh3l3eDW3/Z+WPsLq/JycoQ/HIq86bvqs+5RlGf8Gzkat tMd9DIBe/Q3vs8aPvr+MxL8Uqg46TUE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1728400735; a=rsa-sha256; cv=none; b=K/8pOId7mVDwLiKRpowrRM/inQVtreQY0pr8qnlCc4nzws+LHGk5YenJY2Vv1K3AkQC0fS DjeMN4KTT2Zf7GGAAosLfE185+phluKok6QU5kKLnWIaKV+vEXos5VBRaZA/z/jbB3XEgB 9Yc+pEsIgEt9F95fugGW20sMkljvFS8= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=iAqaFm1a; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf15.hostedemail.com: domain of oleg@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=oleg@redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1728400883; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ruYSLgW7gfmln5kN4ADH0+uUUeJjmQiMQYi2GHJLhGM=; b=iAqaFm1anElBoi4Pb8bawOkyrHLVpoByLOQastX1XowKyxaynBSuPro6ghs7oyl+kjnjT6 cyWE8+HDCFQbjFEs0dowIQYIHIgi2QYM0hKdugN2pIo0hgMnxacvJoJCznpYP745yQej22 PLZk7yDCIdH+x1KdVmnOvhWMTIG/aq8= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-19-BuiWbL8bPueyNVxlgpUhdA-1; Tue, 08 Oct 2024 11:21:22 -0400 X-MC-Unique: BuiWbL8bPueyNVxlgpUhdA-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 19AB51955F3D; Tue, 8 Oct 2024 15:21:19 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.226.71]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 68A7219560A7; Tue, 8 Oct 2024 15:21:12 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 8 Oct 2024 17:21:05 +0200 (CEST) Date: Tue, 8 Oct 2024 17:20:57 +0200 From: Oleg Nesterov To: Andrii Nakryiko Cc: linux-trace-kernel@vger.kernel.org, peterz@infradead.org, rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, willy@infradead.org, surenb@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, mjguzik@gmail.com, brauner@kernel.org, jannh@google.com, mhocko@kernel.org, vbabka@suse.cz, mingo@kernel.org Subject: Re: [PATCH v2 tip/perf/core 0/5] uprobes,mm: speculative lockless VMA-to-uprobe lookup Message-ID: <20241008152056.GA9508@redhat.com> References: <20241001225207.2215639-1-andrii@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241001225207.2215639-1-andrii@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 5A0F3A0004 X-Stat-Signature: ru4siud34ytadd6t9f53seaoe7nh4fsh X-Rspam-User: X-HE-Tag: 1728400884-790745 X-HE-Meta: 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 hg5XxrlA wcT8WeeqCsN+A83Y+I95xTSvlobA5+kkWCRk6O/vwibjrjuzMzrVUFlRbP/QpAb6Db9RdRf4AqeyFgVY5RQoXTdNj9rtR3L4Ows2ocemnDs1XZpfMuTSGdCIw87X4inkqEwKVcfTXV9qqB7oBtnbKKN/+6H4voKOufX4i5TooYv/v9Lddt1KScSADlMx6HxNuX3u5p+1hNI/YDVm8GSwH4DEG1ct9P5F5VWMrMeOG0HVPP1ZORDZtaByzUYjp5xp9M/IvqugJmRnHQgXvWa7IyOoPHGJwbiIPbqxHAzKDCKvS9VpBQFFtFHa5RA== 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: Well. I am in no position to ack these changes. But let me say that I personally like this series and I see nothing wrong, except perhaps 5/5 needs some data_race/etc annotations as we have already discussed. Thanks, Oleg. On 10/01, Andrii Nakryiko wrote: > > Implement speculative (lockless) resolution of VMA to inode to uprobe, > bypassing the need to take mmap_lock for reads, if possible. Patch #1 by Suren > adds mm_struct helpers that help detect whether mm_struct were changed, which > is used by uprobe logic to validate that speculative results can be trusted > after all the lookup logic results in a valid uprobe instance. Patch #2 > follows to make mm_lock_seq into 64-bit counter (on 64-bit architectures). > > Patch #3 adds back RCU-delayed freeing for FMODE_BACKING files, which is > necessary to make speculation safe to access struct file's memory in any > possible situation. > > Patch #4 is a simplification to uprobe VMA flag checking, suggested by Oleg. > > And, finally, patch #5 is the speculative VMA-to-uprobe resolution logic. See > corresponding patch for details and benchmarking results. > > v1->v2: > - adjusted vma_end_write_all() comment to point out it should never be called > manually now, but I wasn't sure how ACQUIRE/RELEASE comments should be > reworded (previously requested by Jann), so I'd appreciate some help there > (Jann); > - int -> long change for mm_lock_seq, as agreed at LPC2024 (Jann, Suren, Liam); > - kfree_rcu_mightsleep() for FMODE_BACKING (Suren, Christian); > - vm_flags simplification in find_active_uprobe_rcu() and > find_active_uprobe_speculative() (Oleg); > - guard(rcu)() simplified find_active_uprobe_speculative() implementation. > > Andrii Nakryiko (4): > mm: switch to 64-bit mm_lock_seq/vm_lock_seq on 64-bit architectures > fs: add back RCU-delayed freeing of FMODE_BACKING file > uprobes: simplify find_active_uprobe_rcu() VMA checks > uprobes: add speculative lockless VMA-to-inode-to-uprobe resolution > > Suren Baghdasaryan (1): > mm: introduce mmap_lock_speculation_{start|end} > > fs/file_table.c | 2 +- > include/linux/mm.h | 6 ++-- > include/linux/mm_types.h | 7 ++-- > include/linux/mmap_lock.h | 72 ++++++++++++++++++++++++++++++++------- > kernel/events/uprobes.c | 46 ++++++++++++++++++++++++- > kernel/fork.c | 3 -- > 6 files changed, 114 insertions(+), 22 deletions(-) > > -- > 2.43.5 >