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authorRoss Lagerwall <ross.lagerwall@citrix.com>2016-03-17 16:52:00 +0000
committerDavid Vrabel <david.vrabel@citrix.com>2016-04-06 11:29:18 +0100
commitdfd74a1edfaba5864276a2859190a8d242d18952 (patch)
treee5c6287363a3b7e75b34c0b84e1ffa422894a0e2 /drivers/xen
parent60901df3aed230d4565dca003f11b6a95fbf30d9 (diff)
xen/balloon: Fix crash when ballooning on x86 32 bit PAE
Commit 55b3da98a40dbb3776f7454daf0d95dde25c33d2 (xen/balloon: find non-conflicting regions to place hotplugged memory) caused a regression in 4.4. When ballooning on an x86 32 bit PAE system with close to 64 GiB of memory, the address returned by allocate_resource may be above 64 GiB. When using CONFIG_SPARSEMEM, this setup is limited to using physical addresses < 64 GiB. When adding memory at this address, it runs off the end of the mem_section array and causes a crash. Instead, fail the ballooning request. Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com> Cc: <stable@vger.kernel.org> # 4.4+ Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/balloon.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 9781e0dd59d6..d46839f51e73 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -151,6 +151,8 @@ static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
static void balloon_process(struct work_struct *work);
static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
+static void release_memory_resource(struct resource *resource);
+
/* When ballooning out (allocating memory to return to Xen) we don't really
want the kernel to try too hard since that can trigger the oom killer. */
#define GFP_BALLOON \
@@ -267,6 +269,20 @@ static struct resource *additional_memory_resource(phys_addr_t size)
return NULL;
}
+#ifdef CONFIG_SPARSEMEM
+ {
+ unsigned long limit = 1UL << (MAX_PHYSMEM_BITS - PAGE_SHIFT);
+ unsigned long pfn = res->start >> PAGE_SHIFT;
+
+ if (pfn > limit) {
+ pr_err("New System RAM resource outside addressable RAM (%lu > %lu)\n",
+ pfn, limit);
+ release_memory_resource(res);
+ return NULL;
+ }
+ }
+#endif
+
return res;
}