On Wed, Apr 16, 2014 at 4:42 PM, Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> wrote: > On Wed, Apr 16, 2014 at 07:52:29AM +0800, Bob Liu wrote: >> > *ptl = pmd_lock(mm, pmd); >> > - if (pmd_none(*pmd)) >> > + if (!pmd_present(*pmd)) >> > goto unlock; >> >> But I didn't get the idea why pmd_none() was removed? > > !pmd_present(*pmd) is weaker check then pmd_none(*pmd). I mean if > pmd_none(*pmd) is true then pmd_present(*pmd) is always false. Oh, yes. That's right. BTW, it looks like this bug was introduced by the same reason. https://lkml.org/lkml/2014/4/16/403 -- Regards, --Bob -- 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>