From: Mateusz Guzik <mjguzik@gmail.com>
To: Jann Horn <jannh@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>,
Christian Brauner <brauner@kernel.org>,
Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>,
linux-trace-kernel@vger.kernel.org, peterz@infradead.org,
oleg@redhat.com, rostedt@goodmis.org, mhiramat@kernel.org,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
jolsa@kernel.org, paulmck@kernel.org, willy@infradead.org,
akpm@linux-foundation.org, linux-mm@kvack.org
Subject: Re: [PATCH RFC v3 13/13] uprobes: add speculative lockless VMA to inode resolution
Date: Thu, 15 Aug 2024 21:07:26 +0200 [thread overview]
Message-ID: <CAGudoHETsUtwR=KJpMCEfbZazxv-FbYgMSe_Lk4MV0CVg0h9ow@mail.gmail.com> (raw)
In-Reply-To: <CAG48ez2VwmFU7ubongD1AnYJDf2-RrFod33Zvbjy1NwRj4-Y1A@mail.gmail.com>
On Thu, Aug 15, 2024 at 8:58 PM Jann Horn <jannh@google.com> wrote:
> Stupid question: Is this uprobe stuff actually such a hot codepath
> that it makes sense to optimize it to be faster than the page fault
> path?
>
That's what I implicitly asked, hoping a down_read on vma would do it,
but Andrii claims multiple parallel lookups on the same vma are a
problem.
Even so, I suspect something *simple* is doable here which avoids any
writes to vmas and does not need the mm-wide sequence counter. It may
be requirements are lax enough that merely observing some state is the
same before and after uprobe lookup will be sufficient, or maybe some
other hackery is viable without messing with fences in
vma_start_write.
--
Mateusz Guzik <mjguzik gmail.com>
next prev parent reply other threads:[~2024-08-15 19:07 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-13 4:29 [PATCH v3 00/13] uprobes: RCU-protected hot path optimizations Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 01/13] uprobes: revamp uprobe refcounting and lifetime management Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 02/13] uprobes: protected uprobe lifetime with SRCU Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 03/13] uprobes: get rid of enum uprobe_filter_ctx in uprobe filter callbacks Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 04/13] uprobes: travers uprobe's consumer list locklessly under SRCU protection Andrii Nakryiko
2024-08-22 14:22 ` Jiri Olsa
2024-08-22 16:59 ` Andrii Nakryiko
2024-08-22 17:35 ` Jiri Olsa
2024-08-22 17:51 ` Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 05/13] perf/uprobe: split uprobe_unregister() Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 06/13] rbtree: provide rb_find_rcu() / rb_find_add_rcu() Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 07/13] uprobes: perform lockless SRCU-protected uprobes_tree lookup Andrii Nakryiko
2024-08-13 4:29 ` [PATCH v3 08/13] uprobes: switch to RCU Tasks Trace flavor for better performance Andrii Nakryiko
2024-08-13 4:29 ` [PATCH RFC v3 09/13] uprobes: SRCU-protect uretprobe lifetime (with timeout) Andrii Nakryiko
2024-08-19 13:41 ` Oleg Nesterov
2024-08-19 20:34 ` Andrii Nakryiko
2024-08-20 15:05 ` Oleg Nesterov
2024-08-20 18:01 ` Andrii Nakryiko
2024-08-13 4:29 ` [PATCH RFC v3 10/13] uprobes: implement SRCU-protected lifetime for single-stepped uprobe Andrii Nakryiko
2024-08-13 4:29 ` [PATCH RFC v3 11/13] mm: introduce mmap_lock_speculation_{start|end} Andrii Nakryiko
2024-08-13 4:29 ` [PATCH RFC v3 12/13] mm: add SLAB_TYPESAFE_BY_RCU to files_cache Andrii Nakryiko
2024-08-13 6:07 ` Mateusz Guzik
2024-08-13 14:49 ` Suren Baghdasaryan
2024-08-13 18:15 ` Andrii Nakryiko
2024-08-13 4:29 ` [PATCH RFC v3 13/13] uprobes: add speculative lockless VMA to inode resolution Andrii Nakryiko
2024-08-13 6:17 ` Mateusz Guzik
2024-08-13 15:36 ` Suren Baghdasaryan
2024-08-15 13:44 ` Mateusz Guzik
2024-08-15 16:47 ` Andrii Nakryiko
2024-08-15 17:45 ` Suren Baghdasaryan
2024-08-15 18:24 ` Mateusz Guzik
2024-08-15 18:58 ` Jann Horn
2024-08-15 19:07 ` Mateusz Guzik [this message]
2024-08-15 19:17 ` Arnaldo Carvalho de Melo
2024-08-15 19:18 ` Arnaldo Carvalho de Melo
2024-08-15 19:44 ` Suren Baghdasaryan
2024-08-15 20:17 ` Andrii Nakryiko
2024-08-15 13:24 ` [PATCH v3 00/13] uprobes: RCU-protected hot path optimizations Oleg Nesterov
2024-08-15 16:49 ` Andrii Nakryiko
2024-08-21 16:41 ` Andrii Nakryiko
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