Messages in this thread | | | From | Joel Fernandes <> | Date | Sat, 2 Sep 2023 22:03:28 -0400 | Subject | Re: [PATCH 2/2] rcu: Dump vmalloc memory info safely |
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On Sat, Sep 2, 2023 at 9:28 PM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Wed, 30 Aug 2023 11:04:00 +0000 "Joel Fernandes (Google)" <joel@joelfernandes.org> wrote: > > > Currently, for double invoke call_rcu(), will dump rcu_head objects > > memory info, if the objects is not allocated from the slab allocator, > > the vmalloc_dump_obj() will be invoke and the vmap_area_lock spinlock > > need to be held, since the call_rcu() can be invoked in interrupt context, > > therefore, there is a possibility of spinlock deadlock scenarios. > > > > And in Preempt-RT kernel, the rcutorture test also trigger the following > > lockdep warning: > > "possibility of deadlock" sounds like something -stable kernels would > like to have fixed. > > Did you consider the desirability of a -stable backport? > > If so, are we able to identify a suitable Fixes: target?
Good point, it should be: Fixes: 98f180837a89 ("mm: Make mem_dump_obj() handle vmalloc() memory")
I am currently reworking the patch as Vlad was also concerned about (the existing) issue of accessing vm_struct fields without holding the lock [1].
I will add this fixes tag to both patches for the v3 on the respin.
Thanks!
- Joel
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