The patch titled
Subject: drivers/base/memory: fix an unlikely reference counting issue in __add_memory_block()
has been added to the -mm tree. Its filename is
drivers-base-memory-fix-an-unlikely-reference-counting-issue-in-__add_memory_block.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/drivers-base-memory-fix-an-unlikely-reference-counting-issue-in-__add_memory_block.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/drivers-base-memory-fix-an-unlikely-reference-counting-issue-in-__add_memory_block.patch
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------------------------------------------------------
From: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Subject: drivers/base/memory: fix an unlikely reference counting issue in __add_memory_block()
__add_memory_block() calls both put_device() and device_unregister() when
storing the memory block into the xarray. This is incorrect because
xarray doesn't take an additional reference and device_unregister()
already calls put_device().
Triggering the issue looks really unlikely and its only effect should be
to log a spurious warning about a ref counted issue.
Link: https://lkml.kernel.org/r/d44c63d78affe844f020dc02ad6af29abc448fc4.1650611702.git.christophe.jaillet@xxxxxxxxxx
Fixes: 4fb6eabf1037 ("drivers/base/memory.c: cache memory blocks in xarray to accelerate lookup")
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
Cc: Scott Cheloha <cheloha@xxxxxxxxxxxxxxxxxx>
Cc: Nathan Lynch <nathanl@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/memory.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
--- a/drivers/base/memory.c~drivers-base-memory-fix-an-unlikely-reference-counting-issue-in-__add_memory_block
+++ a/drivers/base/memory.c
@@ -636,10 +636,9 @@ static int __add_memory_block(struct mem
}
ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory,
GFP_KERNEL));
- if (ret) {
- put_device(&memory->dev);
+ if (ret)
device_unregister(&memory->dev);
- }
+
return ret;
}
_
Patches currently in -mm which might be from christophe.jaillet@xxxxxxxxxx are
drivers-base-memory-fix-an-unlikely-reference-counting-issue-in-__add_memory_block.patch
