linux-kernel - [PATCH v1] xen/balloon: Set pages PageOffline() in balloon_add

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Date:   Fri, 27 Sep 2019 17:46:28 +0200
From:   David Hildenbrand <david@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-mm@...ck.org, xen-devel@...ts.xenproject.org,
        David Hildenbrand <david@...hat.com>,
        Marek Marczykowski-Górecki 
        <marmarek@...isiblethingslab.com>, stable@...r.kernel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>
Subject: [PATCH v1] xen/balloon: Set pages PageOffline() in balloon_add_region()

We are missing a __SetPageOffline(), which is why we can get
!PageOffline() pages onto the balloon list, where
alloc_xenballooned_pages() will complain:

page:ffffea0003e7ffc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xffffe00001000(reserved)
raw: 000ffffe00001000 dead000000000100 dead000000000200 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: VM_BUG_ON_PAGE(!PageOffline(page))
------------[ cut here ]------------
kernel BUG at include/linux/page-flags.h:744!
invalid opcode: 0000 [#1] SMP NOPTI

Reported-by: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.com>
Tested-by: Marek Marczykowski-Górecki <marmarek@...isiblethingslab.com>
Fixes: 77c4adf6a6df ("xen/balloon: mark inflated pages PG_offline")
Cc: stable@...r.kernel.org # v5.1+
Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc: Juergen Gross <jgross@...e.com>
Cc: Stefano Stabellini <sstabellini@...nel.org>
Signed-off-by: David Hildenbrand <david@...hat.com>
---
 drivers/xen/balloon.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 05b1f7e948ef..29f6256363db 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -687,6 +687,7 @@ static void __init balloon_add_region(unsigned long start_pfn,
 		/* totalram_pages and totalhigh_pages do not
 		   include the boot-time balloon extension, so
 		   don't subtract from it. */
+		__SetPageOffline(page);
 		__balloon_append(page);
 	}
 
-- 
2.21.0