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Axel Rasmussen 153132571f userfaultfd/shmem: support UFFDIO_CONTINUE for shmem 
With this change, userspace can resolve a minor fault within a
shmem-backed area with a UFFDIO_CONTINUE ioctl.  The semantics for this
match those for hugetlbfs - we look up the existing page in the page
cache, and install a PTE for it.

This commit introduces a new helper: mfill_atomic_install_pte.

Why handle UFFDIO_CONTINUE for shmem in mm/userfaultfd.c, instead of in
shmem.c?  The existing userfault implementation only relies on shmem.c for
VM_SHARED VMAs.  However, minor fault handling / CONTINUE work just fine
for !VM_SHARED VMAs as well.  We'd prefer to handle CONTINUE for shmem in
one place, regardless of shared/private (to reduce code duplication).

Why add a new mfill_atomic_install_pte helper?  A problem we have with
continue is that shmem_mfill_atomic_pte() and mcopy_atomic_pte() are
*close* to what we want, but not exactly.  We do want to setup the PTEs in
a CONTINUE operation, but we don't want to e.g.  allocate a new page,
charge it (e.g.  to the shmem inode), manipulate various flags, etc.  Also
we have the problem stated above: shmem_mfill_atomic_pte() and
mcopy_atomic_pte() both handle one-half of the problem (shared / private)
continue cares about.  So, introduce mcontinue_atomic_pte(), to handle all
of the shmem continue cases.  Introduce the helper so it doesn't duplicate
code with mcopy_atomic_pte().

In a future commit, shmem_mfill_atomic_pte() will also be modified to use
this new helper.  However, since this is a bigger refactor, it seems most
clear to do it as a separate change.

Link: https://lkml.kernel.org/r/20210503180737.2487560-5-axelrasmussen@google.com
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Oliver Upton <oupton@google.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Wang Qing <wangqing@vivo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 		2021-06-30 20:47:27 -07:00
..
kasan kasan: add memory corruption identification support for hardware tag-based mode 2021-06-29 10:53:53 -07:00
kfence mm, slub: change run-time assertion in kmalloc_index() to compile-time 2021-06-29 10:53:46 -07:00
Kconfig mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM 2021-06-29 10:53:55 -07:00
Kconfig.debug mm, page_poison: remove CONFIG_PAGE_POISONING_ZERO 2020-12-15 12:13:46 -08:00
Makefile mm: hugetlb: free the vmemmap pages associated with each HugeTLB page 2021-06-30 20:47:25 -07:00
backing-dev.c writeback, cgroup: release dying cgwbs by switching attached inodes 2021-06-29 10:53:48 -07:00
balloon_compaction.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
bootmem_info.c mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c 2021-06-30 20:47:25 -07:00
cleancache.c Driver Core and debugfs changes for 5.3-rc1 2019-07-12 12:24:03 -07:00
cma.c mm: use proper type for cma_[alloc|release] 2021-05-05 11:27:24 -07:00
cma.h mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
cma_debug.c mm/cma: change cma mutex to irq safe spinlock 2021-05-05 11:27:21 -07:00
cma_sysfs.c mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
compaction.c mm: memcontrol: remove the pgdata parameter of mem_cgroup_page_lruvec 2021-06-29 10:53:50 -07:00
debug.c mm/debug: factor PagePoisoned out of __dump_page 2021-06-29 10:53:53 -07:00
debug_page_ref.c
…
debug_vm_pgtable.c mm/debug_vm_pgtable: remove redundant pfn_{pmd/pte}() and fix one comment mistake 2021-06-30 20:47:26 -07:00
dmapool.c mm/dmapool: use DEVICE_ATTR_RO macro 2021-06-29 10:53:52 -07:00
early_ioremap.c mm/early_ioremap.c: use __func__ instead of function name 2021-02-26 09:41:02 -08:00
fadvise.c mm, fadvise: improve the expensive remote LRU cache draining after FADV_DONTNEED 2020-10-13 18:38:29 -07:00
failslab.c mm/failslab.c: by default, do not fail allocations with direct reclaim only 2019-07-12 11:05:43 -07:00
filemap.c mm: charge active memcg when no mm is set 2021-06-29 10:53:50 -07:00
frontswap.c mm/mempool: minor coding style tweaks 2021-05-05 11:27:27 -07:00
gup.c mm: gup: pack has_pinned in MMF_HAS_PINNED 2021-06-29 10:53:48 -07:00
gup_test.c selftests/vm: gup_test: test faulting in kernel, and verify pinnable pages 2021-05-05 11:27:26 -07:00
gup_test.h selftests/vm: gup_test: fix test flag 2021-05-05 11:27:26 -07:00
highmem.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
hmm.c mm: do page fault accounting in handle_mm_fault 2020-08-12 10:58:02 -07:00
huge_memory.c mm/userfaultfd: fix uffd-wp special cases for fork() 2021-06-30 20:47:27 -07:00
hugetlb.c hugetlb: address ref count racing in prep_compound_gigantic_page 2021-06-30 20:47:27 -07:00
hugetlb_cgroup.c hugetlb: make free_huge_page irq safe 2021-05-05 11:27:22 -07:00
hugetlb_vmemmap.c mm: hugetlb: introduce CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON 2021-06-30 20:47:26 -07:00
hugetlb_vmemmap.h mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate 2021-06-30 20:47:25 -07:00
hwpoison-inject.c mm,hwpoison-inject: don't pin for hwpoison_filter 2020-10-16 11:11:16 -07:00
init-mm.c mm/gup: prevent gup_fast from racing with COW during fork 2020-12-15 12:13:39 -08:00
internal.h mm/page_alloc: allow high-order pages to be stored on the per-cpu lists 2021-06-29 10:53:55 -07:00
interval_tree.c mm/interval_tree: add comments to improve code readability 2021-04-30 11:20:38 -07:00
io-mapping.c mm: add a io_mapping_map_user helper 2021-04-30 11:20:39 -07:00
ioremap.c mm/ioremap: fix iomap_max_page_shift 2021-05-14 19:41:32 -07:00
khugepaged.c mm/huge_memory.c: add missing read-only THP checking in transparent_hugepage_enabled() 2021-06-30 20:47:26 -07:00
kmemleak.c mm/kmemleak: fix possible wrong memory scanning period 2021-06-29 10:53:47 -07:00
ksm.c mm/ksm: use vma_lookup() in find_mergeable_vma() 2021-06-29 10:53:52 -07:00
list_lru.c mm: vmscan: consolidate shrinker_maps handling code 2021-05-05 11:27:23 -07:00
maccess.c uaccess: add force_uaccess_{begin,end} helpers 2020-08-12 10:57:59 -07:00
madvise.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
mapping_dirty_helpers.c mm/mapping_dirty_helpers: guard hugepage pud's usage 2021-04-16 16:10:37 -07:00
memblock.c mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA 2021-06-29 10:53:55 -07:00
memcontrol.c loop: charge i/o to mem and blk cg 2021-06-29 10:53:50 -07:00
memfd.c mm: page cache: store only head pages in i_pages 2019-09-24 15:54:08 -07:00
memory-failure.c mm/hwpoison: disable pcp for page_handle_poison() 2021-06-30 20:47:27 -07:00
memory.c userfaultfd/shmem: support minor fault registration for shmem 2021-06-30 20:47:27 -07:00
memory_hotplug.c mm: sparsemem: use huge PMD mapping for vmemmap pages 2021-06-30 20:47:26 -07:00
mempolicy.c mm/vmstat: convert NUMA statistics to basic NUMA counters 2021-06-29 10:53:54 -07:00
mempool.c mm/mempool: minor coding style tweaks 2021-05-05 11:27:27 -07:00
memremap.c mm/memremap.c: fix improper SPDX comment style 2021-04-30 11:20:37 -07:00
memtest.c
…
migrate.c mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY 2021-06-30 20:47:26 -07:00
mincore.c inode: make init and permission helpers idmapped mount aware 2021-01-24 14:27:16 +01:00
mlock.c mm/mempool: minor coding style tweaks 2021-05-05 11:27:27 -07:00
mm_init.c include/linux/page-flags-layout.h: cleanups 2021-04-30 11:20:42 -07:00
mmap.c mm/mmap: use find_vma_intersection() in do_mmap() for overlap 2021-06-29 10:53:51 -07:00
mmap_lock.c mm: mmap_lock: use local locks instead of disabling preemption 2021-06-29 10:53:47 -07:00
mmu_gather.c mm: eliminate "expecting prototype" kernel-doc warnings 2021-04-16 16:10:36 -07:00
mmu_notifier.c mm/mmu_notifiers: ensure range_end() is paired with range_start() 2021-03-25 09:22:55 -07:00
mmzone.c mm/lru: replace pgdat lru_lock with lruvec lock 2020-12-15 14:48:04 -08:00
mprotect.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
mremap.c mm/mremap: use vma_lookup() in vma_to_resize() 2021-06-29 10:53:52 -07:00
msync.c mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start 2021-04-30 11:20:37 -07:00
nommu.c mm: ignore MAP_EXECUTABLE in ksys_mmap_pgoff() 2021-06-29 10:53:50 -07:00
oom_kill.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
page-writeback.c fs: remove noop_set_page_dirty() 2021-06-29 10:53:48 -07:00
page_alloc.c hugetlb: address ref count racing in prep_compound_gigantic_page 2021-06-30 20:47:27 -07:00
page_counter.c mm: page_counter: mitigate consequences of a page_counter underflow 2021-04-30 11:20:38 -07:00
page_ext.c mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM 2021-06-29 10:53:55 -07:00
page_idle.c mm: page_idle_get_page() does not need lru_lock 2020-12-15 14:48:03 -08:00
page_io.c swap: fix swapfile read/write offset 2021-03-02 17:25:46 -07:00
page_isolation.c mm/page_isolation: do not isolate the max order page 2020-12-15 12:13:45 -08:00
page_owner.c mm/page_owner: constify dump_page_owner 2021-06-29 10:53:53 -07:00
page_poison.c mm: page_poison: print page info when corruption is caught 2021-04-30 11:20:36 -07:00
page_reporting.c mm/page_reporting: allow driver to specify reporting order 2021-06-29 10:53:47 -07:00
page_reporting.h mm/page_reporting: export reporting order as module parameter 2021-06-29 10:53:47 -07:00
page_vma_mapped.c mm/thp: another PVMW_SYNC fix in page_vma_mapped_walk() 2021-06-24 19:40:53 -07:00
pagewalk.c mm: pagewalk: fix walk for hugepage tables 2021-06-29 10:53:49 -07:00
percpu-internal.h mm: fix typos in comments 2021-05-07 00:26:35 -07:00
percpu-km.c mm: memcg/percpu: account percpu memory to memory cgroups 2020-08-12 10:57:55 -07:00
percpu-stats.c percpu: make pcpu_nr_empty_pop_pages per chunk type 2021-04-09 13:58:38 +00:00
percpu-vm.c mm/vmalloc: remove unmap_kernel_range 2021-04-30 11:20:40 -07:00
percpu.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
pgalloc-track.h mm: fix typos in comments 2021-05-07 00:26:35 -07:00
pgtable-generic.c mm/thp: fix __split_huge_pmd_locked() on shmem migration entry 2021-06-16 09:24:42 -07:00
process_vm_access.c mm/process_vm_access.c: remove duplicate include 2021-05-05 11:27:27 -07:00
ptdump.c mm: ptdump: fix build failure 2021-04-16 16:10:37 -07:00
readahead.c mm: Implement readahead_control pageset expansion 2021-04-23 10:14:29 +01:00
rmap.c mm/thp: fix page_address_in_vma() on file THP tails 2021-06-16 09:24:42 -07:00
rodata_test.c mm/rodata_test.c: fix missing function declaration 2020-08-21 09:52:53 -07:00
shmem.c userfaultfd/shmem: support minor fault registration for shmem 2021-06-30 20:47:27 -07:00
shuffle.c mm: eliminate "expecting prototype" kernel-doc warnings 2021-04-16 16:10:36 -07:00
shuffle.h mm/shuffle: fix section mismatch warning 2021-05-22 15:09:07 -10:00
slab.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
slab.h mm: memcg/slab: properly set up gfp flags for objcg pointer array 2021-06-29 10:53:49 -07:00
slab_common.c mm: memcg/slab: disable cache merging for KMALLOC_NORMAL caches 2021-06-29 10:53:49 -07:00
slob.c mm: Don't build mm_dump_obj() on CONFIG_PRINTK=n kernels 2021-03-08 14:18:46 -08:00
slub.c mm/slub: add taint after the errors are printed 2021-06-29 10:53:47 -07:00
sparse-vmemmap.c mm: sparsemem: split the huge PMD mapping of vmemmap pages 2021-06-30 20:47:26 -07:00
sparse.c mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c 2021-06-30 20:47:25 -07:00
swap.c mm/page_alloc: allow high-order pages to be stored on the per-cpu lists 2021-06-29 10:53:55 -07:00
swap_cgroup.c mm: memcontrol: make swap tracking an integral part of memory control 2020-06-03 20:09:48 -07:00
swap_slots.c mm/swap_slots.c: delete meaningless forward declarations 2021-06-29 10:53:49 -07:00
swap_state.c swap: check mapping_empty() for swap cache before being freed 2021-06-29 10:53:49 -07:00
swapfile.c mm, swap: remove unnecessary smp_rmb() in swap_type_to_swap_info() 2021-06-29 10:53:49 -07:00
truncate.c mm/thp: unmap_mapping_page() to fix THP truncate_cleanup_page() 2021-06-16 09:24:42 -07:00
usercopy.c mm/usercopy.c: delete duplicated word 2020-08-12 10:57:58 -07:00
userfaultfd.c userfaultfd/shmem: support UFFDIO_CONTINUE for shmem 2021-06-30 20:47:27 -07:00
util.c mm/util.c: fix typo 2021-05-05 11:27:25 -07:00
vmacache.c kernel: better document the use_mm/unuse_mm API contract 2020-06-10 19:14:18 -07:00
vmalloc.c mm/vmalloc: enable mapping of huge pages at pte level in vmalloc 2021-06-30 20:47:26 -07:00
vmpressure.c mm: vmpressure: use mem_cgroup_is_root API 2020-04-02 09:35:31 -07:00
vmscan.c mm/page_alloc: limit the number of pages on PCP lists when reclaim is active 2021-06-29 10:53:54 -07:00
vmstat.c mm/vmstat: inline NUMA event counter updates 2021-06-29 10:53:54 -07:00
workingset.c mm: memcontrol: remove the pgdata parameter of mem_cgroup_page_lruvec 2021-06-29 10:53:50 -07:00
z3fold.c mm: fix some typos and code style problems 2021-05-07 00:26:33 -07:00
zbud.c mm: set the sleep_mapped to true for zbud and z3fold 2021-02-26 09:41:01 -08:00
zpool.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
zsmalloc.c mm: fix typos in comments 2021-05-07 00:26:35 -07:00
zswap.c mm/zswap.c: switch from strlcpy to strscpy 2021-05-05 11:27:27 -07:00