Steven Price 8782fb61cc mm: pagewalk: Fix race between unmap and page walker ... The mmap lock protects the page walker from changes to the page tables during the walk. However a read lock is insufficient to protect those areas which don't have a VMA as munmap() detaches the VMAs before downgrading to a read lock and actually tearing down PTEs/page tables. For users of walk_page_range() the solution is to simply call pte_hole() immediately without checking the actual page tables when a VMA is not present. We now never call __walk_page_range() without a valid vma. For walk_page_range_novma() the locking requirements are tightened to require the mmap write lock to be taken, and then walking the pgd directly with 'no_vma' set. This in turn means that all page walkers either have a valid vma, or it's that special 'novma' case for page table debugging. As a result, all the odd '(!walk->vma && !walk->no_vma)' tests can be removed. Fixes: dd2283f260 ("mm: mmap: zap pages with read mmap_sem in munmap") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Steven Price <steven.price@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2022-09-03 10:13:13 -07:00
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cacheflush.c	RISC-V: Do not use cpumask data structure for hartid bitmap	2022-01-20 09:27:22 -08:00
context.c	riscv: Implement sv48 support	2022-01-19 17:54:09 -08:00
dma-noncoherent.c	riscv: implement Zicbom-based CMO instructions + the t-head variant	2022-08-10 20:49:32 -07:00
extable.c	riscv: extable: fix err reg writing in dedicated uaccess handler	2022-02-08 17:02:47 -08:00
fault.c	mm: avoid unnecessary page fault retires on shared memory types	2022-06-16 19:48:27 -07:00
hugetlbpage.c	hugetlbfs: remove hugetlb_add_hstate() warning for existing hstate	2020-06-03 20:09:46 -07:00
init.c	RISC-V: fixups to work with crash tool	2022-08-11 09:04:01 -07:00
kasan_init.c	RISC-V Patches for the 5.18 Merge Window, Part 1	2022-03-25 10:11:38 -07:00
Makefile	riscv: Add support for non-coherent devices using zicbom extension	2022-07-28 15:30:51 -07:00
pageattr.c	mm: pagewalk: Fix race between unmap and page walker	2022-09-03 10:13:13 -07:00
physaddr.c	riscv: Fix DEBUG_VIRTUAL false warnings	2022-03-03 15:32:04 -08:00
ptdump.c	riscv: Fix PTDUMP output now BPF region moved back to module region	2021-07-06 15:21:27 -07:00
tlbflush.c	RISC-V: Do not use cpumask data structure for hartid bitmap	2022-01-20 09:27:22 -08:00