On Tue, Sep 12, 2017 at 09:19:23PM -0400, Boris Ostrovsky wrote: > > > On 09/12/2017 08:01 PM, Konrad Rzeszutek Wilk wrote: > > On Mon, Sep 11, 2017 at 08:45:02PM -0400, Boris Ostrovsky wrote: > > > > > > > > > On 09/11/2017 07:55 PM, Konrad Rzeszutek Wilk wrote: > > > > Hey, > > > > > > > > I've only been able to reproduce this on ARM64 (trying right now ARM32 > > > > as well), and not on x86. > > > > > > > > If I compile Xen without CONFIG_SCRUB_DEBUG it works great. But if > > > > enable it and try to load a livepatch it blows up in page_alloc.c:738 > > > > > > > > This is with origin/staging (d0291f3391) > > > > > > Can you still reproduce this if you revert 307c3be? > > > > Sadly yes - it still crashes. I didn't capture the serial output. > > > > I honestly think the issue is that on ARM64 the "sleep" loop does not > > wake up as often as on x86 (CC-ing Dariof who I believe observed this > > with Credit2 and the wakeup.. something) - maybe he remembers the > > details. Anyhow my theory is that the pages are not scrubbed at all > > when they go in the idle loop as once it goes to sleep - it stays there. > > > There is no (well, should not be) any timing dependencies in how/whether > pages are scrubbed. If a page doesn't get scrubbed because someone didn't > wake up then it should be scrubbed in alloc_heap_pages(). So in this case > the page is thought to be clean (_PGC_need_scrub is not set), but it is not. > > Have you tried running a guest (or two), rebooting in a loop?
No. I just cold-booted it and tried to livepatch. > > Another thing to try is to set need_scrub to true in free_heap_pages(). Magic! diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index dbad1e1ca0..9303eb4517 100644 --- a/xen/common/page_alloc.c +++ b/xen/common/page_alloc.c @@ -1308,6 +1308,7 @@ static void free_heap_pages( ASSERT(node >= 0); spin_lock(&heap_lock); + need_scrub = true; for ( i = 0; i < (1 << order); i++ ) { Fixes it ! :-) > > -boris > > > > > > Ah, see commit 05c52278a7c92bc753d9fe32017e4961012b9f23 > > > > Maybe this is related? > > > > > > > > > -boris _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel