On Thu, Jan 25, 2024 at 2:23 AM kernel test robot <lkp@xxxxxxxxx> wrote: > > tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master > head: 01af33cc9894b4489fb68fa35c40e9fe85df63dc > commit: 0c30c4cd953025979b7689e49844837f762303ec [1589/1892] mm/maps: read proc/pid/maps under RCU > config: x86_64-randconfig-121-20240125 (https://download.01.org/0day-ci/archive/20240125/202401251829.0m6Eo4LI-lkp@xxxxxxxxx/config) > compiler: clang version 17.0.6 (https://github.com/llvm/llvm-project 6009708b4367171ccdbf4b5905cb6a803753fe18) > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240125/202401251829.0m6Eo4LI-lkp@xxxxxxxxx/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new version of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot <lkp@xxxxxxxxx> > | Closes: https://lore.kernel.org/oe-kbuild-all/202401251829.0m6Eo4LI-lkp@xxxxxxxxx/ > > sparse warnings: (new ones prefixed by >>) > >> fs/proc/task_mmu.c:143:45: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected struct file [noderef] __rcu **f @@ got struct file ** @@ Uh, this is a problem. I missed that get_file_rcu() is used only with mm->exe_file and vma->vm_file is not really RCU-safe. It's freed via a call to fput() which schedules its freeing using schedule_delayed_work(..., 1) but I don't think that constitutes RCU grace period. Paul, Matthew, could you please confirm? In the meantime I'm going to ask Andrew to remove my patchset from mm-unstable to be safe. > fs/proc/task_mmu.c:143:45: sparse: expected struct file [noderef] __rcu **f > fs/proc/task_mmu.c:143:45: sparse: got struct file ** > fs/proc/task_mmu.c: note: in included file (through include/linux/rbtree.h, include/linux/mm_types.h, include/linux/mmzone.h, ...): > include/linux/rcupdate.h:781:9: sparse: sparse: context imbalance in 'get_vma_snapshot' - unexpected unlock > fs/proc/task_mmu.c:264:22: sparse: sparse: context imbalance in 'm_start' - different lock contexts for basic block > include/linux/rcupdate.h:781:9: sparse: sparse: context imbalance in 'm_stop' - unexpected unlock > include/linux/rcupdate.h:781:9: sparse: sparse: context imbalance in 'smaps_pte_range' - unexpected unlock > include/linux/rcupdate.h:781:9: sparse: sparse: context imbalance in 'clear_refs_pte_range' - unexpected unlock > include/linux/rcupdate.h:781:9: sparse: sparse: context imbalance in 'pagemap_pmd_range' - unexpected unlock > include/linux/rcupdate.h:781:9: sparse: sparse: context imbalance in 'pagemap_scan_pmd_entry' - unexpected unlock > fs/proc/task_mmu.c: note: in included file (through arch/x86/include/asm/uaccess.h, include/linux/uaccess.h, include/linux/sched/task.h, ...): > arch/x86/include/asm/uaccess_64.h:88:24: sparse: sparse: cast removes address space '__user' of expression > arch/x86/include/asm/uaccess_64.h:88:24: sparse: sparse: cast removes address space '__user' of expression > > vim +143 fs/proc/task_mmu.c > > 132 > 133 /* > 134 * Take VMA snapshot and pin vm_file and anon_name as they are used by > 135 * show_map_vma. > 136 */ > 137 static int get_vma_snapshot(struct proc_maps_private *priv, struct vm_area_struct *vma) > 138 { > 139 struct vm_area_struct *copy = &priv->vma_copy; > 140 int ret = -EAGAIN; > 141 > 142 memcpy(copy, vma, sizeof(*vma)); > > 143 if (copy->vm_file && !get_file_rcu(©->vm_file)) > 144 goto out; > 145 > 146 if (!anon_vma_name_get_if_valid(copy)) > 147 goto put_file; > 148 > 149 if (priv->mm_wr_seq == mmap_write_seq_read(priv->mm)) > 150 return 0; > 151 > 152 /* Address space got modified, vma might be stale. Wait and retry. */ > 153 rcu_read_unlock(); > 154 ret = mmap_read_lock_killable(priv->mm); > 155 mmap_write_seq_record(priv->mm, &priv->mm_wr_seq); > 156 mmap_read_unlock(priv->mm); > 157 rcu_read_lock(); > 158 > 159 if (!ret) > 160 ret = -EAGAIN; /* no other errors, ok to retry */ > 161 > 162 anon_vma_name_put_if_valid(copy); > 163 put_file: > 164 if (copy->vm_file) > 165 fput(copy->vm_file); > 166 out: > 167 return ret; > 168 } > 169 > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki
