On Tue, 4 Sep 2012 11:41:21 +0300 Haggai Eran <haggaie@xxxxxxxxxxxx> wrote: > In order to allow sleeping during invalidate_page mmu notifier calls, we > need to avoid calling when holding the PT lock. In addition to its > direct calls, invalidate_page can also be called as a substitute for a > change_pte call, in case the notifier client hasn't implemented > change_pte. > > This patch drops the invalidate_page call from change_pte, and instead > wraps all calls to change_pte with invalidate_range_start and > invalidate_range_end calls. > > Note that change_pte still cannot sleep after this patch, and that > clients implementing change_pte should not take action on it in case the > number of outstanding invalidate_range_start calls is larger than one, > otherwise they might miss a later invalidation. > > ... > > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -145,6 +145,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, > /* For try_to_free_swap() and munlock_vma_page() below */ > lock_page(page); > > + mmu_notifier_invalidate_range_start(mm, addr, addr + PAGE_SIZE); > err = -EAGAIN; > ptep = page_check_address(page, mm, addr, &ptl, 0); > if (!ptep) > @@ -173,6 +174,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, > > err = 0; > unlock: > + mmu_notifier_invalidate_range_end(mm, addr, addr + PAGE_SIZE); > unlock_page(page); > return err; > } Again, now I have to apply the patch and peer at the code to work out whether `addr' got changed anywhere between these two calls. And I somehow need to ensure that `addr' will not get modified in the future and I can't do that! -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>