From: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
Subject: drivers/base/memory.c: prohibit offlining of memory blocks with missing sections
bdee237c ("x86: mm: Use 2GB memory block size on large-memory x86-64
systems") and 982792c7 ("x86, mm: probe memory block size for generic x86
64bit") introduced large block sizes for x86. This made it possible to
have multiple sections per memory block where previously, there was a only
every one section per block.
Since blocks consist of contiguous ranges of section, there can be holes
in the blocks where sections are not present. If one attempts to offline
such a block, a crash occurs since the code is not designed to deal with
this.
This patch is a quick fix to gaurd against the crash by not allowing
blocks with non-present sections to be offlined.
Addresses https://bugzilla.kernel.org/show_bug.cgi?id=107781
Signed-off-by: Seth Jennings <sjennings@xxxxxxxxxxxxxx>
Reported-by: Andrew Banman <abanman@xxxxxxx>
Cc: Daniel J Blueman <daniel@xxxxxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Greg KH <greg@xxxxxxxxx>
Cc: Russ Anderson <rja@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/memory.c | 4 ++++
1 file changed, 4 insertions(+)
diff -puN drivers/base/memory.c~drivers-memory-prohibit-offlining-of-memory-blocks-with-missing-sections drivers/base/memory.c
--- a/drivers/base/memory.c~drivers-memory-prohibit-offlining-of-memory-blocks-with-missing-sections
+++ a/drivers/base/memory.c
@@ -303,6 +303,10 @@ static int memory_subsys_offline(struct
if (mem->state == MEM_OFFLINE)
return 0;
+ /* Can't offline block with non-present sections */
+ if (mem->section_count != sections_per_block)
+ return -EINVAL;
+
return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
}
_
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