The quilt patch titled Subject: mm: add a call to flush_cache_vmap() in vmap_pfn() has been removed from the -mm tree. Its filename was mm-add-a-call-to-flush_cache_vmap-in-vmap_pfn.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------ From: Alexandre Ghiti alexghiti@rivosinc.com Subject: mm: add a call to flush_cache_vmap() in vmap_pfn() Date: Wed, 9 Aug 2023 18:46:33 +0200
flush_cache_vmap() must be called after new vmalloc mappings are installed in the page table in order to allow architectures to make sure the new mapping is visible.
It could lead to a panic since on some architectures (like powerpc), the page table walker could see the wrong pte value and trigger a spurious page fault that can not be resolved (see commit f1cb8f9beba8 ("powerpc/64s/radix: avoid ptesync after set_pte and ptep_set_access_flags")).
But actually the patch is aiming at riscv: the riscv specification allows the caching of invalid entries in the TLB, and since we recently removed the vmalloc page fault handling, we now need to emit a tlb shootdown whenever a new vmalloc mapping is emitted (https://lore.kernel.org/linux-riscv/20230725132246.817726-1-alexghiti@rivosi...). That's a temporary solution, there are ways to avoid that :)
Link: https://lkml.kernel.org/r/20230809164633.1556126-1-alexghiti@rivosinc.com Fixes: 3e9a9e256b1e ("mm: add a vmap_pfn function") Reported-by: Dylan Jhong dylan@andestech.com Closes: https://lore.kernel.org/linux-riscv/ZMytNY2J8iyjbPPy@atctrx.andestech.com/ Signed-off-by: Alexandre Ghiti alexghiti@rivosinc.com Reviewed-by: Christoph Hellwig hch@lst.de Reviewed-by: Palmer Dabbelt palmer@rivosinc.com Acked-by: Palmer Dabbelt palmer@rivosinc.com Reviewed-by: Dylan Jhong dylan@andestech.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/vmalloc.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/mm/vmalloc.c~mm-add-a-call-to-flush_cache_vmap-in-vmap_pfn +++ a/mm/vmalloc.c @@ -2979,6 +2979,10 @@ void *vmap_pfn(unsigned long *pfns, unsi free_vm_area(area); return NULL; } + + flush_cache_vmap((unsigned long)area->addr, + (unsigned long)area->addr + count * PAGE_SIZE); + return area->addr; } EXPORT_SYMBOL_GPL(vmap_pfn); _
Patches currently in -mm which might be from alexghiti@rivosinc.com are