On Wed, 19 Aug 2020, Greg KH wrote: > On Wed, Aug 19, 2020 at 06:32:26AM -0700, Hugh Dickins wrote: > > On Wed, 19 Aug 2020, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > > > > > This is a note to let you know that I've just added the patch titled > > > > > > khugepaged: khugepaged_test_exit() check mmget_still_valid() > > > > > > to the 5.8-stable tree which can be found at: > > > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > > > > > The filename of the patch is: > > > khugepaged-khugepaged_test_exit-check-mmget_still_valid.patch > > > and it can be found in the queue-5.8 subdirectory. > > > > > > If you, or anyone else, feels it should not be added to the stable tree, > > > please let <stable@xxxxxxxxxxxxxxx> know about it. > > > > Please hold this one back for the moment: we shall want it, but syzbot > > detected one place where it can lead to a VM_BUG_ON_MM(). The fix to > > that is currently in Andrew's tree, but not yet in Linus's - when it > > gets there, I'll send you its git commit id in reply to this mail. > > > > This patch failed to apply to earlier releases: I'll send the fixup for > > those at that time. (Fixups for another patch to follow later today.) > > Now dropped, thanks! f3f99d63a815 khugepaged: adjust VM_BUG_ON_MM() in __khugepaged_enter() has now reached Linus's tree, so will reach your tree when you next pull. When that one is ready, please reinstate this commit that we held back: bbe98f9cadff khugepaged: khugepaged_test_exit() check mmget_still_valid() The mmap_sem->mmap_lock change means I must then send you a backport of bbe98f9cadff for 5.7, 5.4, 4.19, 4.14, 4.9: one backport will do for all of those, and f3f99d63a815 should cherry-pick cleanly into them all. But you also marked bbe98f9cadff for 4.4: I had not expected that, but I think you're right - for whatever reason (probably inertia, it was tiresome because khugepaged.c got split from huge_memory.c), 4.4 lacks a backport of 59ea6d06cfa9 (though it does have the commit that depended on), and backports of these two will serve just as well to fix what it was required to fix: I'll send them too. Thanks: I'm sorry that this is all so confusing, kudos to syzbot for catching my error as quickly as it did. Hugh
