From 6f84f8d1587f20f60592cf1b1792ca639f37d429 Mon Sep 17 00:00:00 2001
From: Pavel Tatashin <pasha.tatashin@oracle.com>
Date: Tue, 10 Apr 2018 16:36:10 -0700
Subject: xen, mm: allow deferred page initialization for xen pv domains

Juergen Gross noticed that commit f7f99100d8d ("mm: stop zeroing memory
during allocation in vmemmap") broke XEN PV domains when deferred struct
page initialization is enabled.

This is because the xen's PagePinned() flag is getting erased from
struct pages when they are initialized later in boot.

Juergen fixed this problem by disabling deferred pages on xen pv
domains.  It is desirable, however, to have this feature available as it
reduces boot time.  This fix re-enables the feature for pv-dmains, and
fixes the problem the following way:

The fix is to delay setting PagePinned flag until struct pages for all
allocated memory are initialized, i.e.  until after free_all_bootmem().

A new x86_init.hyper op init_after_bootmem() is called to let xen know
that boot allocator is done, and hence struct pages for all the
allocated memory are now initialized.  If deferred page initialization
is enabled, the rest of struct pages are going to be initialized later
in boot once page_alloc_init_late() is called.

xen_after_bootmem() walks page table's pages and marks them pinned.

Link: http://lkml.kernel.org/r/20180226160112.24724-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Tested-by: Juergen Gross <jgross@suse.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Jinbum Park <jinb.park7@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Jia Zhang <zhang.jia@linux.alibaba.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/page_alloc.c | 4 ----
 1 file changed, 4 deletions(-)

(limited to 'mm')

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b4390db64da3..905db9d7962f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -46,7 +46,6 @@
 #include <linux/stop_machine.h>
 #include <linux/sort.h>
 #include <linux/pfn.h>
-#include <xen/xen.h>
 #include <linux/backing-dev.h>
 #include <linux/fault-inject.h>
 #include <linux/page-isolation.h>
@@ -317,9 +316,6 @@ static inline bool update_defer_init(pg_data_t *pgdat,
 	/* Always populate low zones for address-constrained allocations */
 	if (zone_end < pgdat_end_pfn(pgdat))
 		return true;
-	/* Xen PV domains need page structures early */
-	if (xen_pv_domain())
-		return true;
 	(*nr_initialised)++;
 	if ((*nr_initialised > pgdat->static_init_pgcnt) &&
 	    (pfn & (PAGES_PER_SECTION - 1)) == 0) {
-- 
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