On 9/11/19 8:57 PM, Matthew Wilcox wrote: > On Wed, Sep 11, 2019 at 04:05:37PM +0100, Waiman Long wrote: >> To remove the unacceptable delays, we have to limit the amount of wait >> time on the mmap_sem. So the new down_write_timedlock() function is >> used to acquire the write lock on the mmap_sem with a timeout value of >> 10ms which should not cause a perceivable delay. If timeout happens, >> the task will abandon its effort to share the PMD and allocate its own >> copy instead. > If you do a v2, this is *NOT* the mmap_sem. It's the i_mmap_rwsem > which protects a very different data structure from the mmap_sem. > Thanks for reminder. I should have read the code more carefully. Cheers, Longman
