Messages in this thread | | | Subject | Re: [Xen-devel] [PATCH] mm: fix regression with deferred struct page init | From | Juergen Gross <> | Date | Thu, 27 Jun 2019 17:35:39 +0200 |
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On 25.06.19 10:25, Juergen Gross wrote: > Gentle ping. > > I'd really like to have that in 5.2 in order to avoid the regression > introduced with 5.2-rc1.
Adding some maintainers directly...
Juergen
> > > Juergen > > On 20.06.19 18:08, Juergen Gross wrote: >> Commit 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time >> instead of doing larger sections") is causing a regression on some >> systems when the kernel is booted as Xen dom0. >> >> The system will just hang in early boot. >> >> Reason is an endless loop in get_page_from_freelist() in case the first >> zone looked at has no free memory. deferred_grow_zone() is always >> returning true due to the following code snipplet: >> >> /* If the zone is empty somebody else may have cleared out the zone */ >> if (!deferred_init_mem_pfn_range_in_zone(&i, zone, &spfn, &epfn, >> first_deferred_pfn)) { >> pgdat->first_deferred_pfn = ULONG_MAX; >> pgdat_resize_unlock(pgdat, &flags); >> return true; >> } >> >> This in turn results in the loop as get_page_from_freelist() is >> assuming forward progress can be made by doing some more struct page >> initialization. >> >> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> >> Fixes: 0e56acae4b4dd4a9 ("mm: initialize MAX_ORDER_NR_PAGES at a time >> instead of doing larger sections") >> Suggested-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> >> Signed-off-by: Juergen Gross <jgross@suse.com> >> --- >> mm/page_alloc.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index d66bc8abe0af..8e3bc949ebcc 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -1826,7 +1826,8 @@ deferred_grow_zone(struct zone *zone, unsigned >> int order) >> first_deferred_pfn)) { >> pgdat->first_deferred_pfn = ULONG_MAX; >> pgdat_resize_unlock(pgdat, &flags); >> - return true; >> + /* Retry only once. */ >> + return first_deferred_pfn != ULONG_MAX; >> } >> /* >> > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xenproject.org > https://lists.xenproject.org/mailman/listinfo/xen-devel
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