On Mon, Apr 09, 2012 at 11:40:31AM +0300, Pekka Enberg wrote: > On Mon, 2012-04-09 at 03:38 +0400, Anton Vorontsov wrote: > > vmevent grabs a mutex in the atomic context, and so this pops up: > > > > BUG: sleeping function called from invalid context at kernel/mutex.c:271 > > in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/0 [...] > > This patch fixes the issue by removing the mutex and making the logic > > lock-free. > > > > Signed-off-by: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx> > > What guarantees that there's only one thread writing to struct > vmevent_attr::value in vmevent_sample() now that the mutex is gone? Well, it is called from the timer function, which has the same guaranties as an interrupt handler: it can have only one execution thread (unlike bare softirq handler), so we don't need to worry about racing w/ ourselves? If you're concerned about several instances of timers accessing the same vmevent_watch, I don't really see how it is possible, as we allocate vmevent_watch together w/ the timer instance in vmevent_fd(), so there is always one timer per vmevent_watch. Thanks, -- Anton Vorontsov Email: cbouatmailru@xxxxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>