Re: [PATCH] tracing: Fix WARN_ON in tracing_buffers_mmap_close

[Steven Rostedt]

On Fri, 27 Feb 2026 10:41:17 +0000
Vincent Donnefort <vdonnefort@xxxxxxxxxx> wrote:

> > Hum, not sure this is entirely correct. We do set VM_DONTCOPY when creating the
> > mapping (see __rb_map_vma). So AFAICT ->open() is not called in this situation (see
> > dup_mmap())  
> 
> Ah right, Syzkaller is using madvise(MADVISE_DOFORK) which resets VM_DONTCOPY.

Hmm,

So this means user space can override the DONTCOPY? Can this cause bugs
elsewhere that DONTCOPY is used?

-- Steve