On top of mm-unstable. VM_PAT annoyed me too much and wasted too much of my time, let's clean PAT handling up and remove VM_PAT.
This should sort out various issues with VM_PAT we discovered recently, and will hopefully make the whole code more stable and easier to maintain. In essence: we stop letting PAT mode mess with VMAs and instead lift what to track/untrack to the MM core. We remember per VMA which pfn range we tracked in a new struct we attach to a VMA (we have space without exceeding 192 bytes), use a kref to share it among VMAs during split/mremap/fork, and automatically untrack once the kref drops to 0. This implies that we'll keep tracking a full pfn range even after partially unmapping it, until fully unmapping it; but as that case was mostly broken before, this at least makes it work in a way that is least intrusive to VMA handling. Shrinking with mremap() used to work in a hacky way, now we'll similarly keep the original pfn range tacked even after this form of partial unmap. Does anybody care about that? Unlikely. If we run into issues, we could likely handled that (adjust the tracking) when our kref drops to 1 while freeing a VMA. But it adds more complexity, so avoid that for now. Briefly tested There will be some clash with [1], but nothing that cannot be sorted out easily by moving the functions added to kernel/fork.c to wherever the vma bits will live. Briefly tested with some basic /dev/mem test I crafted. I want to convert them to selftests, but that might or might not require a bit of more work (e.g., /dev/mem accessibility). [1] lkml.kernel.org/r/[email protected] Cc: Dave Hansen <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Jani Nikula <[email protected]> Cc: Joonas Lahtinen <[email protected]> Cc: Rodrigo Vivi <[email protected]> Cc: Tvrtko Ursulin <[email protected]> Cc: David Airlie <[email protected]> Cc: Simona Vetter <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Mathieu Desnoyers <[email protected]> Cc: "Liam R. Howlett" <[email protected]> Cc: Lorenzo Stoakes <[email protected]> Cc: Vlastimil Babka <[email protected]> Cc: Jann Horn <[email protected]> Cc: Pedro Falcato <[email protected]> Cc: Peter Xu <[email protected]> David Hildenbrand (11): x86/mm/pat: factor out setting cachemode into pgprot_set_cachemode() mm: convert track_pfn_insert() to pfnmap_sanitize_pgprot() x86/mm/pat: introduce pfnmap_track() and pfnmap_untrack() mm/memremap: convert to pfnmap_track() + pfnmap_untrack() mm: convert VM_PFNMAP tracking to pfnmap_track() + pfnmap_untrack() x86/mm/pat: remove old pfnmap tracking interface mm: remove VM_PAT x86/mm/pat: remove strict_prot parameter from reserve_pfn_range() x86/mm/pat: remove MEMTYPE_*_MATCH drm/i915: track_pfn() -> "pfnmap tracking" mm/io-mapping: track_pfn() -> "pfnmap tracking" arch/x86/mm/pat/memtype.c | 194 ++++------------------------- arch/x86/mm/pat/memtype_interval.c | 44 +------ drivers/gpu/drm/i915/i915_mm.c | 4 +- include/linux/mm.h | 4 +- include/linux/mm_inline.h | 2 + include/linux/mm_types.h | 11 ++ include/linux/pgtable.h | 101 ++++++--------- include/trace/events/mmflags.h | 4 +- kernel/fork.c | 54 +++++++- mm/huge_memory.c | 7 +- mm/io-mapping.c | 2 +- mm/memory.c | 85 ++++++++++--- mm/memremap.c | 8 +- mm/mremap.c | 4 - 14 files changed, 212 insertions(+), 312 deletions(-) -- 2.49.0
