FAILED: patch "[PATCH] libnvdimm/pmem: Fix crash triggered when I/O in-flight during" failed to apply to 5.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 32b2397c1e56f33b0b1881def965bb89bd12f448 Mon Sep 17 00:00:00 2001
From: sumiyawang <sumiyawang@tencent.com>
Date: Sun, 22 Aug 2021 19:49:09 +0800
Subject: [PATCH] libnvdimm/pmem: Fix crash triggered when I/O in-flight during
 unbind

There is a use after free crash when the pmem driver tears down its
mapping while I/O is still inbound.

This is triggered by driver unbind, "ndctl destroy-namespace", while I/O
is in flight.

Fix the sequence of blk_cleanup_queue() vs memunmap().

The crash signature is of the form:

 BUG: unable to handle page fault for address: ffffc90080200000
 CPU: 36 PID: 9606 Comm: systemd-udevd
 Call Trace:
  ? pmem_do_bvec+0xf9/0x3a0
  ? xas_alloc+0x55/0xd0
  pmem_rw_page+0x4b/0x80
  bdev_read_page+0x86/0xb0
  do_mpage_readpage+0x5d4/0x7a0
  ? lru_cache_add+0xe/0x10
  mpage_readpages+0xf9/0x1c0
  ? bd_link_disk_holder+0x1a0/0x1a0
  blkdev_readpages+0x1d/0x20
  read_pages+0x67/0x1a0

  ndctl Call Trace in vmcore:
  PID: 23473  TASK: ffff88c4fbbe8000  CPU: 1   COMMAND: "ndctl"
  __schedule
  schedule
  blk_mq_freeze_queue_wait
  blk_freeze_queue
  blk_cleanup_queue
  pmem_release_queue
  devm_action_release
  release_nodes
  devres_release_all
  device_release_driver_internal
  device_driver_detach
  unbind_store

Cc: <stable@vger.kernel.org>
Signed-off-by: sumiyawang <sumiyawang@tencent.com>
Reviewed-by: yongduan <yongduan@tencent.com>
Link: https://lore.kernel.org/r/1629632949-14749-1-git-send-email-sumiyawang@tencent.com
Fixes: 50f44ee7248a ("mm/devm_memremap_pages: fix final page put race")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 1e0615b8565e..72de88ff0d30 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -450,11 +450,11 @@ static int pmem_attach_disk(struct device *dev,
 		pmem->pfn_flags |= PFN_MAP;
 		bb_range = pmem->pgmap.range;
 	} else {
+		addr = devm_memremap(dev, pmem->phys_addr,
+				pmem->size, ARCH_MEMREMAP_PMEM);
 		if (devm_add_action_or_reset(dev, pmem_release_queue,
 					&pmem->pgmap))
 			return -ENOMEM;
-		addr = devm_memremap(dev, pmem->phys_addr,
-				pmem->size, ARCH_MEMREMAP_PMEM);
 		bb_range.start =  res->start;
 		bb_range.end = res->end;
 	}