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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 715AB80012 X-Rspamd-Server: rspam12 X-Stat-Signature: ry49q77xuce74nmy63xw5yn8zy6mmqn7 X-Rspam-User: X-HE-Tag: 1735383649-933221 X-HE-Meta: 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 aHMdpQfR CajAMZ55XpeSwAn2LMdij4egoxJ315r63MYpsduLk9nXsq0Kk8Dui77wgfcdP4LDRhGrxH9AXndYqdWxlq/nOeDMaZ2M0ZM3C6tFdOEJ/IwWfKf4tXRC/zOpujr9IrRRWKvLLGVPZJNCrkfUmk16TueErKbB5PNaQT7j0eY3QimrWxDuuiJ2zMv4r2I43cqVm5Z2JncRDZlUy6f/WkiacoE+5/wk8WUOd2rv3RQrbyn+PJ2sX7iMVtdhG75uYm0zY9UHVJSM4PXK2r8pGt2atpKDhfk/Rlg9//lRsUBOIYy1zKGak3FrYnzJ4/CJ617I1YnoWpKJbfQWoNNZfu5LQAsamSliHGvp9mS20zTZvhVhwJ9jb1AEGVuHAYoKA+lDAfLN7 X-Bogosity: Ham, tests=bogofilter, spamicity=0.163011, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 28 Dec 2024 01:52:28 -0800 Boqun Feng > On Fri, Dec 27, 2024 at 06:03:45PM -0800, Suren Baghdasaryan wrote: > > On Fri, Dec 27, 2024 at 4:19 PM Hillf Danton wrote: > > > On Fri, 27 Dec 2024 04:59:22 -0800 > > > > > > > > CPU0 CPU1 > > > > ---- ---- > > > > lock(&po->pg_vec_lock); > > > > lock(&mm->mmap_lock); > > > > lock(&po->pg_vec_lock); > > > > lock(&vma->vm_lock->lock); > > > > > > > > *** DEADLOCK *** > > > > > > > > 2 locks held by syz.8.396/8273: > > > > #0: ffff0000d6a2cc10 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline] > > > > #0: ffff0000d6a2cc10 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x154/0x38c mm/util.c:578 > > > > #1: ffff0000d4aa2868 (&po->pg_vec_lock){+.+.}-{4:4}, at: packet_mmap+0x9c/0x4c8 net/packet/af_packet.c:4650 > > > > > > > Given &mm->mmap_lock and &po->pg_vec_lock in same locking order on both sides, > > > this deadlock report is bogus. Due to lockdep glitch? > > What do you mean by "both sides"? Note that, here is the report saying CPU0/1 in the lockdep diagram above. > the locks that are already held by the current task, and that current > task is going to acquire &vma->vm_lock->lock, so lockdep finds new > dependency: Note the current task acquires &po->pg_vec_lock after taking &mm->mmap_lock, and it is the &mm->mmap_lock (ignored by lockdep?) that makes the report look bogus. > > &po->pg_vec_lock --> &vma->vm_lock->lock > > and there will be a circular dependency because (see above) lockdep > recorded a dependency chain that: > > &vma->vm_lock->lock --> ... --> &po->pg_vec_lock