Messages in this thread | | | Date | Thu, 13 Dec 2018 10:43:14 +0100 | From | Greg Kurz <> | Subject | Re: [PATCH] radix tree: Don't return internal entries on lookup |
| |
On Thu, 6 Dec 2018 17:21:02 +0100 Greg Kurz <groug@kaod.org> wrote:
> On Thu, 6 Dec 2018 05:36:20 -0800 > Matthew Wilcox <willy@infradead.org> wrote: > > > On Thu, Dec 06, 2018 at 08:54:03AM +0100, Greg Kurz wrote: > > > Commit 66ee620f06f9 ("idr: Permit any valid kernel pointer to > > > be stored") changed the radix tree lookup so that it stops when > > > reaching the bottom of the tree. But radix_tree_descend() may have > > > changed the node variable to point to an internal entry which then > > > gets returned to the caller and bad things may happen. > > > > > pe_data is equal to R3 which is the return value of radix_tree_lookup(), > > > ie, 0x406 == RADIX_TREE_RETRY. > > > > Thank you for the report and the debugging! I've decided to fix the > > problem slightly differently, and I've also added a test to the test-suite > > Heh this is the fix I came up with initially, but then I wasn't sure > if other kind of internal entries could possibly be returned by > radix_tree_descend() so I tried to be smarter... I should have sticked > to my initial intuition :) > > > that reproduces the problem in only a few iterations (the largest I've > > seen is a few hundred; and often it'll reproduce in under twenty). > > > > You can see it here: > > http://git.infradead.org/users/willy/linux-dax.git/commitdiff/eff3860bbfedbac6edac57fb0d7f3a60e860c1c3 > > > > You can add: > > Reviewed-by: Greg Kurz <groug@kaod.org> > Tested-by: Greg Kurz <groug@kaod.org> > > > I'll give the build bots a couple of days to chew on it and then ask > > Linus to pull it. >
Hi Matthew and Andrew,
I see this fix is in linux-next. I just want to make sure it will land in 4.20 in order to avoid kernel panics in the OCXL driver.
Cheers,
-- Greg
> Great ! > > Cheers, > > -- > Greg
| |