>> With CONFIG_SPARSEMEM_EXTREME, the root memory section descriptors >> are allocated by slab or bootmem allocator. Also, the descriptors >> might have been allocated and initialized during the hotplug path. >> However, the memory chunk allocated in current implementation wouldn't >> be put into the available pool if that has been allocated. The situation >> will lead to memory leak. > >I've read this changelog about ten times and I'm still not really clear >what the bug is here. > yep, I need improve my written English definitely :-) >-- > >sparse_index_init() is designed to be safe if two copies of it race. It >uses "index_init_lock" to ensure that, even in the case of a race, only >one CPU will manage to do: > > mem_section[root] = section; > >However, in the case where two copies of sparse_index_init() _do_ race, >the one that loses the race will leak the "section" that >sparse_index_alloc() allocated for it. This patch fixes that leak. > >-- Thank you very much, Dave. Let me merge your changelog into next version. > >Technically, I'm not sure that we can race during the time when we'd be >using bootmem. I think we do all those initializations single-threaded >at the moment, and we'd finish them before we turn the slab on. So, >technically, we probably don't need the bootmem stuff in >sparse_index_free(). But, I guess it doesn't hurt, and it's fine for >completeness. > >Gavin, have you actually tested this in some way? It looks OK to me, >but I worry that you've just added a block of code that's exceedingly >unlikely to get run. I didn't test this and I just catch the point while reading the source code. By the way, I would like to know the popular utilities used for memory testing. If you can share some information regarding that, that would be great. - memory related benchmark testing utility. - some documents on Linux memory testing. Thanks, Gavin -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>