The patch titled Subject: blackfin: a couple of task->mm handling fixes has been removed from the -mm tree. Its filename was blackfin-a-couple-of-task-mm-handling-fixes.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx> Subject: blackfin: a couple of task->mm handling fixes The patch fixes two problems: 1. Working with task->mm w/o getting mm or grabing the task lock is dangerous as ->mm might disappear (exit_mm() assigns NULL under task_lock(), so tasklist lock is not enough). We can't use get_task_mm()/mmput() pair as mmput() might sleep, so we have to take the task lock while handle its mm. 2. Checking for process->mm is not enough because process' main thread may exit or detach its mm via use_mm(), but other threads may still have a valid mm. To catch this we use find_lock_task_mm(), which walks up all threads and returns an appropriate task (with task lock held). Suggested-by: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx> Cc: Mike Frysinger <vapier@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/blackfin/kernel/trace.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) diff -puN arch/blackfin/kernel/trace.c~blackfin-a-couple-of-task-mm-handling-fixes arch/blackfin/kernel/trace.c --- a/arch/blackfin/kernel/trace.c~blackfin-a-couple-of-task-mm-handling-fixes +++ a/arch/blackfin/kernel/trace.c @@ -10,6 +10,8 @@ #include <linux/hardirq.h> #include <linux/thread_info.h> #include <linux/mm.h> +#include <linux/oom.h> +#include <linux/sched.h> #include <linux/uaccess.h> #include <linux/module.h> #include <linux/kallsyms.h> @@ -28,7 +30,6 @@ void decode_address(char *buf, unsigned struct task_struct *p; struct mm_struct *mm; unsigned long flags, offset; - unsigned char in_atomic = (bfin_read_IPEND() & 0x10) || in_atomic(); struct rb_node *n; #ifdef CONFIG_KALLSYMS @@ -114,15 +115,15 @@ void decode_address(char *buf, unsigned */ write_lock_irqsave(&tasklist_lock, flags); for_each_process(p) { - mm = (in_atomic ? p->mm : get_task_mm(p)); - if (!mm) - continue; + struct task_struct *t; - if (!down_read_trylock(&mm->mmap_sem)) { - if (!in_atomic) - mmput(mm); + t = find_lock_task_mm(p); + if (!t) continue; - } + + mm = t->mm; + if (!down_read_trylock(&mm->mmap_sem)) + goto __continue; for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) { struct vm_area_struct *vma; @@ -131,7 +132,7 @@ void decode_address(char *buf, unsigned if (address >= vma->vm_start && address < vma->vm_end) { char _tmpbuf[256]; - char *name = p->comm; + char *name = t->comm; struct file *file = vma->vm_file; if (file) { @@ -164,8 +165,7 @@ void decode_address(char *buf, unsigned name, vma->vm_start, vma->vm_end); up_read(&mm->mmap_sem); - if (!in_atomic) - mmput(mm); + task_unlock(t); if (buf[0] == '\0') sprintf(buf, "[ %s ] dynamic memory", name); @@ -175,8 +175,8 @@ void decode_address(char *buf, unsigned } up_read(&mm->mmap_sem); - if (!in_atomic) - mmput(mm); +__continue: + task_unlock(t); } /* _ Patches currently in -mm which might be from anton.vorontsov@xxxxxxxxxx are origin.patch blackfin-fix-possible-deadlock-in-decode_address.patch um-should-hold-tasklist_lock-while-traversing-processes.patch um-fix-possible-race-on-task-mm.patch um-properly-check-all-process-threads-for-a-live-mm.patch kernel-cpuc-document-clear_tasks_mm_cpumask.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