Before this patch, passing a range that is beyond the physical memory
range will succeed, the user will see a /dev/pmem0 and will be able to
access it. Reads will always return 0 and writes will be silently
ignored.
I've gotten more than one bug report about mkfs.{xfs,ext4} or nvml
failing that were eventually tracked down to be wrong values passed to
memmap.
This patch prevents the above issue by instead of adding a new memory
range, only update a RAM memory range with the PRAM type. This way,
passing the wrong memmap will either not give you a pmem at all or give
you a smaller one that actually has RAM behind it.
And if someone still needs to fake a pmem that doesn't have RAM behind
it, they can simply do memmap=XX@YY,XX!YY.
Signed-off-by: Yigal Korman <yi...@plexistor.com>
Acked-by: Dan Williams <dan.j.willi...@intel.com>
Acked-by: Johannes Thumshirn <jthumsh...@suse.de>
Tested-by: Boaz Harrosh <b...@plexistor.com>
---
arch/x86/kernel/e820.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 621b501..4bd4207 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -878,7 +878,7 @@ static int __init parse_memmap_one(char *p)
e820_add_region(start_at, mem_size, E820_RESERVED);
} else if (*p == '!') {
start_at = memparse(p+1, &p);
- e820_add_region(start_at, mem_size, E820_PRAM);
+ e820_update_range(start_at, mem_size, E820_RAM, E820_PRAM);
} else
e820_remove_range(mem_size, ULLONG_MAX - mem_size, E820_RAM, 1);
--
1.9.3
