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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: nx3dcwkssogogohgzujmzawrffcnu6km X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 1B68B140017 X-Rspam-User: X-HE-Tag: 1693706620-51287 X-HE-Meta: U2FsdGVkX1+UWOa2OXBIk4cJ3nM3R8HXX3jq+dh+5/9nrlhiBl1/o3s5UzSnoreTJM/BV8xbynP2XTHd18/9sA+q2LfgDL8d4iAkoawV4Pti2A5R+ydWqgBRt18Ina+k1c+NdSeTiufBI5Q95/z4ldcb3OZ+9ntrc+G8BK7A5YQO0W27KVdGuZINTVfIU48HZIk82aYp+O76kILTCNqK0D5zNVSMm9rkf2I9FiDB58ItLd+lyG3U4wxfrkYm+0syfBZ9w0qVsuGi1oRHCU8tBoCv0OhfxXiPRxy+mJj++a5f3fqx+v2G5xTBICUrZV9X9KjftLttx25V7rU3PCRbk1q6QzT4UiPxFDJIMgEJik2iw0b+jBA50iLq/CtuZF+3lLu6bYHmkCaTK2Idxc/lLRk1HSzYmMp5ommctekdhatKDcBh9wk2J0rY7P6nLeh4Z6XXFJgiVAUJnNPP+vURSs6WV2VQnbRE7WnppZ0R8djKhizytKL0DhC3GIoOgzpEhvl75Dof8i+5XWVPj6+XjeIy11kXj+cReTSt0ggimEf9X04m2SFtGNmzukq/D8Ga6AoMMYNvyERj7elzL1/DxZK0etCB1nLiQn2YlcXyGUxibzhijudm7aufAY6qgEz1Hg0K5YAlVMzV3aaudwAr6GFsEOYV+NFZ+UBh4XmiO4oRGigOSnZBtveFo5F+7lhx42Yh6UzJV9ifD2zXS7EDFTcXwRNA7EYl8NzGXqsjoi+BKXI1XQem4ah2v4JDoeV7+k2N9+E17BwK47OEGjOEuAjYiMkfPSr55/hHYwF8IIlmPhVCABWfUpA52R1j5qjzs5aVauOnarV5118hx3UR9sEOPZOBwnVNeLQTogQ4UQdWgIM+ogEhcMcGo/f6rLooLFtIhduFlIw9Awc1UdykoGN2AmNKJ33DdpYnR3wNnsNGMcmaeRJqfrghtRhbNSz1AthODdG1FqXvzWXzgTU 81KRcY4W wq19weOL1UKtnIebY1nrDEw6F1g7QI5A1Xjof089WqHy/f6fgO+lma5KGF0VCmXlFsi/qbijogzCoEeem9I/U2v/ZAXSJdzLu96qWcLlsEgUzBTyYJZrFBceu1NU/s1IwveKwVSCbB6064Mb+YjCy2ZRr7idr7Tw9jjead6XLbMKgXOwSqosJ3eTuyK0JM7XAcMWV99gYX5PWXbvzaluTwRApBnkDkQTRBKKogb9a16DX90UCtgQBgFB7LjQpA2S/gfSoHV+7hKWB8aRcO8T0BEvqkRvqVjciDv9tdeQy0dQQQz8P1e2ijDVqiDE0y3HPFk+BPKWDwwZraxQk5Rm8GnimAjoPxZVSEO8uWrhh9QZlWq5dHSFF9+zcOqC3oTnrAvTWGdQU0Pmnsr9Zttpi05aNZ9MK+7C3quXS 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 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 conte= xt, > > therefore, there is a possibility of spinlock deadlock scenarios. > > > > And in Preempt-RT kernel, the rcutorture test also trigger the followin= g > > 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