forked from luck/tmp_suning_uos_patched
dcb73bf402
Recent enhancement of rb-tree based lookup exposed a bug with the lookup mechanism in the reserve_memtype() which ensures that there are no conflicting memtype requests for the memory range. memtype_rb_search() returns an entry which has a start address <= new start address. And from here we traverse the linear linked list to check if there any conflicts with the existing mappings. As the rbtree is based on the start address of the memory range, it is quite possible that we have several overlapped mappings whose start address is much less than new requested start but the end is >= new requested end. This results in conflicting memtype mappings. Same bug exists with the old code which uses cached_entry from where we traverse the linear linked list. But the new rb-tree code exposes this bug fairly easily. For now, don't use the memtype_rb_search() and always start the search from the head of linear linked list in reserve_memtype(). Linear linked list for most of the systems grow's to few 10's of entries(as we track memory type of RAM pages using struct page). So we should be ok for now. We still retain the rbtree and use it to speed up free_memtype() which doesn't have the same bug(as we know what exactly we are searching for in free_memtype). Also use list_for_each_entry_from() in free_memtype() so that we start the search from rb-tree lookup result. Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> LKML-Reference: <1253136483.4119.12.camel@sbs-t61.sc.intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com> |
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