lkml.org 
[lkml]   [2016]   [Mar]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] uprobes: wait for mmap_sem for write killable
From
Date
On 02/29/2016 06:42 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> xol_add_vma needs mmap_sem for write. If the waiting task gets killed by
> the oom killer it would block oom_reaper from asynchronous address space
> reclaim and reduce the chances of timely OOM resolving. Wait for the
> lock in the killable mode and return with EINTR if the task got killed
> while waiting.
>
> Do not warn in dup_xol_work if __create_xol_area failed due to fatal
> signal pending because this is usually considered a kernel issue.
>
> Cc: Oleg Nesterov <oleg@redhat.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
> kernel/events/uprobes.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 8eef5f55d3f0..fb4a6bcc88ce 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1130,7 +1130,9 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
> struct vm_area_struct *vma;
> int ret;
>
> - down_write(&mm->mmap_sem);
> + if (down_write_killable(&mm->mmap_sem))
> + return -EINTR;
> +
> if (mm->uprobes_state.xol_area) {
> ret = -EALREADY;
> goto fail;
> @@ -1468,7 +1470,8 @@ static void dup_xol_work(struct callback_head *work)
> if (current->flags & PF_EXITING)
> return;
>
> - if (!__create_xol_area(current->utask->dup_xol_addr))
> + if (!__create_xol_area(current->utask->dup_xol_addr) &&
> + !fatal_signal_pending(current)
^ missing ")"

Other than that,
Acked-by: Vlastimil Babka <vbabka@suse.cz>

> uprobe_warn(current, "dup xol area");
> }
>
>

\
 
 \ /
  Last update: 2016-03-11 16:41    [W:0.280 / U:0.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site