On Mon, Jul 3, 2023 at 6:52 AM Holger Hoffstätte
<holger@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> On 2023-07-03 12:47, Jiri Slaby wrote:
> > Cc Jacob Young (from kernel bugzilla)
> >
> > On 30. 06. 23, 19:40, Suren Baghdasaryan wrote:
> >> On Fri, Jun 30, 2023 at 1:43 AM Jiri Slaby <jirislaby@xxxxxxxxxx> wrote:
> >>>
> >>> On 30. 06. 23, 10:28, Jiri Slaby wrote:
> >>>> > 2348
> >>>> clone3({flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|CLONE_SYSVSEM|CLONE_SETTLS|CLONE_PARENT_SETTID|CLONE_CHILD_CLEARTID, child_tid=0x7fcaa5882990, parent_tid=0x7fcaa5882990, exit_signal=0, stack=0x7fcaa5082000, stack_size=0x7ffe00, tls=0x7fcaa58826c0} => {parent_tid=[2351]}, 88) = 2351
> >>>> > 2350 <... clone3 resumed> => {parent_tid=[2372]}, 88) = 2372
> >>>> > 2351 <... clone3 resumed> => {parent_tid=[2354]}, 88) = 2354
> >>>> > 2351 <... clone3 resumed> => {parent_tid=[2357]}, 88) = 2357
> >>>> > 2354 <... clone3 resumed> => {parent_tid=[2355]}, 88) = 2355
> >>>> > 2355 <... clone3 resumed> => {parent_tid=[2370]}, 88) = 2370
> >>>> > 2370 mmap(NULL, 262144, PROT_READ|PROT_WRITE,
> >>>> MAP_PRIVATE|MAP_ANONYMOUS, -1, 0 <unfinished ...>
> >>>> > 2370 <... mmap resumed>) = 0x7fca68249000
> >>>> > 2372 <... clone3 resumed> => {parent_tid=[2384]}, 88) = 2384
> >>>> > 2384 <... clone3 resumed> => {parent_tid=[2388]}, 88) = 2388
> >>>> > 2388 <... clone3 resumed> => {parent_tid=[2392]}, 88) = 2392
> >>>> > 2392 <... clone3 resumed> => {parent_tid=[2395]}, 88) = 2395
> >>>> > 2395 write(2, "runtime: marked free object in s"..., 36 <unfinished
> >>>> ...>
> >>>>
> >>>> I.e. IIUC, all are threads (CLONE_VM) and thread 2370 mapped ANON
> >>>> 0x7fca68249000 - 0x7fca6827ffff and go in thread 2395 thinks for some
> >>>> reason 0x7fca6824bec8 in that region is "bad".
> >>
> >> Thanks for the analysis Jiri.
> >> Is it possible from these logs to identify whether 2370 finished the
> >> mmap operation before 2395 tried to access 0x7fca6824bec8? That access
> >> has to happen only after mmap finishes mapping the region.
> >
> > Hi,
> >
> > it's hard to tell, but I assume so.
> >
> > For now, forget about this go's overly complicated, hard to reproduce case and concentrate on the very nice reduced testcase in:
> > https://bugzilla.kernel.org/show_bug.cgi?id=217624
> > ;)
> >
> > FWIW, I can reproduce using the test case too.
Thanks for the reproducer, Jiri!
Let me try it and see if I can figure this one out.
> >
> > thanks,
>
> As another (admittedly correlation-only) data point, I noticed at least hourly crashes
> of Firefox-114 after upgrading to 6.4.1, which had never happened before with 6.3.x.
> After reverting 0bff0aaea03e2a3ed6 - with a bit of context fixup due to follow-up
> commits in 6.4.1 - it has been rock stable again, for several hours now.
>
> cheers
> Holger
