On Thu, May 22, 2025 at 11:48:22PM +0900, Masami Hiramatsu wrote: > On Tue, 20 May 2025 16:19:26 +0200 > Oleg Nesterov <o...@redhat.com> wrote: > > > On 05/20, Masami Hiramatsu wrote: > > > > > > On Thu, 15 May 2025 14:10:58 +0200 > > > Jiri Olsa <jo...@kernel.org> wrote: > > > > > > > Currently unapply_uprobe takes mmap_read_lock, but it might call > > > > remove_breakpoint which eventually changes user pages. > > > > > > > > Current code writes either breakpoint or original instruction, so > > > > it can probably go away with that, but with the upcoming change that > > > > writes multiple instructions on the probed address we need to ensure > > > > that any update to mm's pages is exclusive. > > > > > > > > > > So, this is a bugfix, right? > > > > No, mmap_read_lock() is fine. > > > > To remind, this was already discussed with you, see > > [PATCH 02/12] uprobes: grab write mmap lock in unapply_uprobe() > > https://lore.kernel.org/all/20240625002144.3485799-3-and...@kernel.org/ > > > > And you even reviewed this patch > > [PATCH 1/2] uprobes: document the usage of mm->mmap_lock > > https://lore.kernel.org/all/20240710140045.ga1...@redhat.com/ > > > > But, as the changelog explains, this patch is needed for the upcoming > > changes. > > Oops, OK. So current code is good with either mmap_read_lock() or > mmap_write_lock(). > But the patch description is a bit confusing. If the point is an atomic > (byte?) > update or not, it should describe it.
ok, I'll try to make the changelog more detailed thanks, jirka > > Thank you, > > > > > -------------------------------------------------------------------------- > > Just in case... I'll try to read this series tomorrow, but at first glance > > this version addresses all my concerns. > > > > Oleg. > > > > > -- > Masami Hiramatsu (Google) <mhira...@kernel.org>
