Messages in this thread | | | Date | Wed, 16 Nov 2022 23:30:50 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] perf: Fix sys_perf_event_open() race against self |
| |
On Mon, May 23, 2022 at 04:03:29PM +0530, Ravi Bangoria wrote: > On 21-May-22 12:08 AM, Peter Zijlstra wrote: > > > > Norbert reported that it's possible to race sys_perf_event_open() such > > that the looser ends up in another context from the group leader, > > triggering many WARNs. > > > > The move_group case checks for races against itself, but the > > !move_group case doesn't, seemingly relying on the previous > > group_leader->ctx == ctx check. However, that check is racy due to not > > holding any locks at that time. > > > > Therefore, re-check the result after acquiring locks and bailing > > if they no longer match. > > > > Additionally, clarify the not_move_group case from the > > move_group-vs-move_group race. > > Tested-by: Ravi Bangoria <ravi.bangoria@amd.com> > > Below is a quick test to reproduce the issue. It triggers WARN_ON() > as normal user. No warnings with the patch.
Shouldn't this test be in tools/perf/tests/ or so?
If that hasn't happened yet, I mean.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
| |