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McKenney" , rcu@vger.kernel.org, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: 9hn7nu1eadop9bup8j88cndp37u8bisi X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: D9B4040010 X-Rspam-User: X-HE-Tag: 1693706721-199125 X-HE-Meta: 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 MxtekbCK 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Sep 2, 2023 at 10:03=E2=80=AFPM Joel Fernandes wrote: > > On Sat, Sep 2, 2023 at 9:28=E2=80=AFPM Andrew Morton wrote: > > > > On Wed, 30 Aug 2023 11:04:00 +0000 "Joel Fernandes (Google)" 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 con= text, > > > therefore, there is a possibility of spinlock deadlock scenarios. > > > > > > And in Preempt-RT kernel, the rcutorture test also trigger the follow= ing > > > 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. > Sigh, I missed sharing the link to [1]: [1] https://lore.kernel.org/all/20230901003321.GA3389909@google.com/ thanks, - Joel