xen/balloon: Fix crash when ballooning on x86 32 bit PAE
Commit 55b3da98a4
(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>
This commit is contained in:
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@ -151,6 +151,8 @@ static DECLARE_WAIT_QUEUE_HEAD(balloon_wq);
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static void balloon_process(struct work_struct *work);
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static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
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static void release_memory_resource(struct resource *resource);
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/* When ballooning out (allocating memory to return to Xen) we don't really
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want the kernel to try too hard since that can trigger the oom killer. */
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#define GFP_BALLOON \
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@ -267,6 +269,20 @@ static struct resource *additional_memory_resource(phys_addr_t size)
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return NULL;
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}
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#ifdef CONFIG_SPARSEMEM
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{
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unsigned long limit = 1UL << (MAX_PHYSMEM_BITS - PAGE_SHIFT);
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unsigned long pfn = res->start >> PAGE_SHIFT;
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if (pfn > limit) {
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pr_err("New System RAM resource outside addressable RAM (%lu > %lu)\n",
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pfn, limit);
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release_memory_resource(res);
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return NULL;
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}
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}
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#endif
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return res;
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}
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