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Patch "dax: fix device-dax region base" has been added to the 4.7-stable tree

PATCH [email protected] 1 participant 1 message Sep 5, 2016

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This is a note to let you know that I've just added the patch titled

dax: fix device-dax region base

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
dax-fix-device-dax-region-base.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From d0e5845561c238619de9f5b77e0d763f4c331ca5 Mon Sep 17 00:00:00 2001

From: Dan Williams <[email protected]>
Date: Thu, 25 Aug 2016 15:17:14 -0700
Subject: dax: fix device-dax region base

From: Dan Williams <[email protected]>

commit d0e5845561c238619de9f5b77e0d763f4c331ca5 upstream.

The data offset for a dax region needs to account for a reservation in the resource range. Otherwise, device-dax is allowing mappings directly into the memmap or device-info-block area with crash signatures like the following:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
 IP: get_zone_device_page+0x11/0x30
 Call Trace:
   follow_devmap_pmd+0x298/0x2c0
   follow_page_mask+0x275/0x530
   __get_user_pages+0xe3/0x750
   __gfn_to_pfn_memslot+0x1b2/0x450 [kvm]
   tdp_page_fault+0x130/0x280 [kvm]
   kvm_mmu_page_fault+0x5f/0xf0 [kvm]
   handle_ept_violation+0x94/0x180 [kvm_intel]
   vmx_handle_exit+0x1d3/0x1440 [kvm_intel]
   kvm_arch_vcpu_ioctl_run+0x81d/0x16a0 [kvm]
   kvm_vcpu_ioctl+0x33c/0x620 [kvm]
   do_vfs_ioctl+0xa2/0x5d0
   SyS_ioctl+0x79/0x90
   entry_SYSCALL_64_fastpath+0x1a/0xa4
Fixes ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory")
Link http://lkml.kernel.org/r/147205536732.1606.8994275381938837346.stgit@dwillia2-desk3.amr.corp.intel.com open here
Signed-off-by Dan Williams <[email protected]>
Reported-by Abhilash Kumar Mulumudi <[email protected]>
Reported-by Toshi Kani <[email protected]>
Tested-by Toshi Kani <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
Signed-off-by Linus Torvalds <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/dax/pmem.c |    3 +++
 1 file changed, 3 insertions(+)
drivers/dax/pmem.c +3 -0
@@ -118,6 +118,9 @@ static int dax_pmem_probe(struct device
 		return rc;
 	}
 
+	/* adjust the dax_region resource to the start of data */
+	res.start += le64_to_cpu(pfn_sb->dataoff);
+
 	nd_region = to_nd_region(dev->parent);
 	dax_region = alloc_dax_region(dev, nd_region->id, &res,
 			le32_to_cpu(pfn_sb->align), addr, PFN_DEV|PFN_MAP);

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/libnvdimm-nd_blk-mask-off-reserved-status-bits.patch queue-4.7/mm-silently-skip-readahead-for-dax-inodes.patch queue-4.7/dax-fix-device-dax-region-base.patch queue-4.7/tools-testing-nvdimm-fix-sigterm-vs-hotplug-crash.patch