On Thu, Dec 22, 2016 at 10:15:20AM +0100, Michal Hocko wrote: >On Wed 21-12-16 23:30:33, Wei Yang wrote: >> memblock_reserve() would add a new range to memblock.reserved in case the >> new range is not totally covered by any of the current memblock.reserved >> range. If the memblock.reserved is full and can't resize, >> memblock_reserve() would fail. >> >> This doesn't happen in real world now, I observed this during code review. >> While theoretically, it has the chance to happen. And if it happens, others >> would think this range of memory is still available and may corrupt the >> memory. > >OK, this explains it much better than the previous version! The silent >memory corruption is indeed too hard to debug to have this open even >when the issue is theoretical. >
Thanks~ Have a nice day:-) >> This patch checks the return value and goto "done" after it succeeds. >> >> Signed-off-by: Wei Yang <[email protected]> > >Acked-by: Michal Hocko <[email protected]> > >Thanks! > >> --- >> mm/memblock.c | 6 ++---- >> 1 file changed, 2 insertions(+), 4 deletions(-) >> >> diff --git a/mm/memblock.c b/mm/memblock.c >> index 4929e06..d0f2c96 100644 >> --- a/mm/memblock.c >> +++ b/mm/memblock.c >> @@ -1274,18 +1274,17 @@ static void * __init memblock_virt_alloc_internal( >> >> if (max_addr > memblock.current_limit) >> max_addr = memblock.current_limit; >> - >> again: >> alloc = memblock_find_in_range_node(size, align, min_addr, max_addr, >> nid, flags); >> - if (alloc) >> + if (alloc && !memblock_reserve(alloc, size)) >> goto done; >> >> if (nid != NUMA_NO_NODE) { >> alloc = memblock_find_in_range_node(size, align, min_addr, >> max_addr, NUMA_NO_NODE, >> flags); >> - if (alloc) >> + if (alloc && !memblock_reserve(alloc, size)) >> goto done; >> } >> >> @@ -1303,7 +1302,6 @@ static void * __init memblock_virt_alloc_internal( >> >> return NULL; >> done: >> - memblock_reserve(alloc, size); >> ptr = phys_to_virt(alloc); >> memset(ptr, 0, size); >> >> -- >> 2.5.0 > >-- >Michal Hocko >SUSE Labs -- Wei Yang Help you, Help me
