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/cover.1745528282.git.lorenzo.stoa...@oracle.com Cc: Dave Hansen <dave.han...@linux.intel.com> Cc: Andy Lutomirski <l...@kernel.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Ingo Molnar <mi...@redhat.com> Cc: Borislav Petkov <b...@alien8.de> Cc: "H. Peter Anvin" <h...@zytor.com> Cc: Jani Nikula <jani.nik...@linux.intel.com> Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.v...@intel.com> Cc: Tvrtko Ursulin <tursu...@ursulin.net> Cc: David Airlie <airl...@gmail.com> Cc: Simona Vetter <sim...@ffwll.ch> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Steven Rostedt <rost...@goodmis.org> Cc: Masami Hiramatsu <mhira...@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com> Cc: "Liam R. Howlett" <liam.howl...@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoa...@oracle.com> Cc: Vlastimil Babka <vba...@suse.cz> Cc: Jann Horn <ja...@google.com> Cc: Pedro Falcato <pfalc...@suse.de> Cc: Peter Xu <pet...@redhat.com> 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
