The patch titled Subject: fs/proc/task_mmu.c: don't use task->mm in m_start() and show_*map() has been added to the -mm tree. Its filename is fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: fs/proc/task_mmu.c: don't use task->mm in m_start() and show_*map() get_gate_vma(priv->task->mm) looks ugly and wrong, task->mm can be NULL or it can changed by exec right after mm_access(). And in theory this race is not harmless, the task can exec and then later exit and free the new mm_struct. In this case get_task_mm(oldmm) can't help, get_gate_vma(task->mm) can read the freed/unmapped memory. I think that priv->task should simply die and hold_task_mempolicy() logic can be simplified. tail_vma logic asks for cleanups too. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Acked-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/task_mmu.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff -puN fs/proc/task_mmu.c~fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map fs/proc/task_mmu.c --- a/fs/proc/task_mmu.c~fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map +++ a/fs/proc/task_mmu.c @@ -170,7 +170,7 @@ static void *m_start(struct seq_file *m, return mm; down_read(&mm->mmap_sem); - tail_vma = get_gate_vma(priv->task->mm); + tail_vma = get_gate_vma(mm); priv->tail_vma = tail_vma; hold_task_mempolicy(priv); /* Start with last addr hint */ @@ -351,12 +351,11 @@ static int show_map(struct seq_file *m, { struct vm_area_struct *vma = v; struct proc_maps_private *priv = m->private; - struct task_struct *task = priv->task; show_map_vma(m, vma, is_pid); if (m->count < m->size) /* vma is copied successfully */ - m->version = (vma != get_gate_vma(task->mm)) + m->version = (vma != priv->tail_vma) ? vma->vm_start : 0; return 0; } @@ -584,7 +583,6 @@ static void show_smap_vma_flags(struct s static int show_smap(struct seq_file *m, void *v, int is_pid) { struct proc_maps_private *priv = m->private; - struct task_struct *task = priv->task; struct vm_area_struct *vma = v; struct mem_size_stats mss; struct mm_walk smaps_walk = { @@ -639,7 +637,7 @@ static int show_smap(struct seq_file *m, show_smap_vma_flags(m, vma); if (m->count < m->size) /* vma is copied successfully */ - m->version = (vma != get_gate_vma(task->mm)) + m->version = (vma != priv->tail_vma) ? vma->vm_start : 0; return 0; } _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch earlyprintk-re-enable-earlyprintk-calling-early_param.patch fs-proc-task_mmuc-dont-use-task-mm-in-m_start-and-show_map.patch fs-proc-task_mmuc-unify-simplify-do_maps_open-and-numa_maps_open.patch proc-introduce-proc_mem_open.patch fs-proc-task_mmuc-shift-mm_access-from-m_start-to-proc_maps_open.patch fs-proc-task_mmuc-simplify-the-vma_stop-logic.patch fs-proc-task_mmuc-cleanup-the-tail_vma-horror-in-m_next.patch fs-proc-task_mmuc-shift-priv-task-=-null-from-m_start-to-m_stop.patch fs-proc-task_mmuc-kill-the-suboptimal-and-confusing-m-version-logic.patch fs-proc-task_mmuc-simplify-m_start-to-make-it-readable.patch fs-proc-task_mmuc-introduce-m_next_vma-helper.patch fs-proc-task_mmuc-reintroduce-m-version-logic.patch fs-proc-task_mmuc-update-m-version-in-the-main-loop-in-m_start.patch fs-proc-task_nommuc-change-maps_open-to-use-__seq_open_private.patch fs-proc-task_nommuc-shift-mm_access-from-m_start-to-proc_maps_open.patch fs-proc-task_nommuc-dont-use-priv-task-mm.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html