On Wed, May 06, 2009 at 09:42:58PM +0800, Kay Sievers wrote:
> On Mon, May 4, 2009 at 15:30, Wu Fengguang <fengguang.wu@xxxxxxxxx> wrote:
>
> > I tried remove every udev rules in /etc/udev/ and /lib/udev, the /etc/group
> > accesses disappeared in strace, but udevd is still busy.
>
> > ppoll([{fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=3, events=POLLIN}], 3, NULL, [], 8) = 1 ([{fd=3, revents=POLLIN}])
> > ioctl(3, FIONREAD, [39]) = 0
> > read(3, 0x62ad60, 39) = -1 EINVAL (Invalid argument)
>
> Seems, you have issues with inotify on your nfs mount?
>
> Inotify wakes up udevd to tell something in the rules directory has
> changed, but inotify seems not to return anything useful, but keeps
> waking us up. That causes an endless loop of parsing rules files.
Thanks for the tip. The failed inotify read() is caused by the size *roundup*
behavior introduced by the -mm commit 3b46cf7d5f3ca(Reimplement inotify_user
using fsnotify). Which says:
+ /*
+ * We need to pad the filename so as to properly align an
+ * array of inotify_event structures. Because the structure is
+ * small and the common case is a small filename, we just round
+ * up to the next multiple of the structure's sizeof. This is
+ * simple and safe for all architectures.
+ */
The udev madness originates from these kernel testing failures:
[ 756.569243] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.600103] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.630265] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.670862] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.701845] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.732899] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.763126] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.794829] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.824985] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.856760] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 761.608521] __ratelimit: 210 callbacks suppressed
Which are printed by the following patch:
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
size_t count)
{
size_t event_size = sizeof(struct inotify_event);
struct fsnotify_event *event;
if (fsnotify_notify_queue_is_empty(group))
return NULL;
event = fsnotify_peek_notify_event(group);
event_size += roundup(event->name_len, event_size);
- if (event_size > count)
+ if (event_size > count) {
+ if (printk_ratelimit())
+ printk("get_one_event: event_size=%d > count=%d, name_len=%d, name=%s\n",
+ (int)event_size, (int)count, (int)event->name_len, event->file_name);
return ERR_PTR(-EINVAL);
+ }
It can be fixed by reporting the rounded up value to user space.
Thanks,
Fengguang
---
inotify: report rounded-up event size to user space
Fix a udev madness problem, which falls into an endless loop:
(1) ppoll([{fd=4, events=POLLIN}, {fd=5, events=POLLIN}, {fd=3, events=POLLIN}], 3, NULL, [], 8) = 1 ([{fd=3, revents=POLLIN}])
(2) ioctl(3, FIONREAD, [39]) = 0
(3) read(3, 0x62ad60, 39) = -1 EINVAL (Invalid argument)
In (2) we reported a small len, while in (3) we insist on a rounded up len,
leading to a failed inotify read(), which will be retried endlessly by udev.
[ 756.569243] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.600103] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.630265] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.670862] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.701845] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.732899] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.763126] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.794829] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.824985] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 756.856760] get_one_event: event_size=48 > count=38, name_len=22, name=61-dev-root-link.rules
[ 761.608521] __ratelimit: 210 callbacks suppressed
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/notify/inotify/inotify_user.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- linux.orig/fs/notify/inotify/inotify_user.c
+++ linux/fs/notify/inotify/inotify_user.c
@@ -318,7 +318,9 @@ static long inotify_ioctl(struct file *f
mutex_lock(&group->notification_mutex);
list_for_each_entry(holder, &group->notification_list, event_list) {
event = holder->event;
- send_len += sizeof(struct inotify_event) + event->name_len;
+ send_len += sizeof(struct inotify_event);
+ send_len += roundup(event->name_len,
+ sizeof(struct inotify_event));
}
mutex_unlock(&group->notification_mutex);
ret = put_user(send_len, (int __user *) p);
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
