Messages in this thread | | | Date | Thu, 22 Dec 2016 10:15:20 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH 2/2] mm/memblock.c: check return value of memblock_reserve() in memblock_virt_alloc_internal() |
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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.
> This patch checks the return value and goto "done" after it succeeds. > > Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
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
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