__vmap_pages_range_noflush() and friends can install some PTEs before failing and leave them mapped, and the kernel callers do not agree on who cleans them up. pcpu_map_pages() and kmsan_ioremap_page_range() roll back what they mapped before the failure, while vm_module_tags_populate() and the __GFP_NOFAIL retry loop in __vmalloc_area_node() rely on the mapping functions cleaning up and do not call anything like vunmap_range() themselves. When the same range is mapped again, the attempt hits the leftovers and fails, with a BUG() in vmap_pte_range() for huge mappings and a warning on the small-page path.
This moves the rollback into the mapping functions. A failed vmap leaves nothing mapped, and the callers no longer clean up after it. Patch 1 is the KMSAN part. The shadow and the origin of a range are mapped by two separate calls, so the rollback there has to cover both. Patch 2 adds it to __vmap_pages_range_noflush() and vmap_page_range(). Patches 3 and 4 drop the powerpc and percpu cleanups that are not needed anymore. Hao Ge (4): mm/kmsan: undo the shadow mapping when the origin mapping fails mm/vmalloc: undo partial mappings inside the mapping functions powerpc: drop redundant unmaps of failed vmap mappings mm/percpu: stop unmapping the CPU that failed to map arch/powerpc/kernel/isa-bridge.c | 5 ++-- arch/powerpc/kernel/pci_64.c | 4 +-- mm/kmsan/shadow.c | 4 +++ mm/percpu-vm.c | 5 ++-- mm/vmalloc.c | 44 +++++++++++++++++++++++--------- 5 files changed, 42 insertions(+), 20 deletions(-) -- 2.25.1
