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Ross Zwisler 642261ac99 dax: add struct iomap based DAX PMD support 
DAX PMDs have been disabled since Jan Kara introduced DAX radix tree based
locking.  This patch allows DAX PMDs to participate in the DAX radix tree
based locking scheme so that they can be re-enabled using the new struct
iomap based fault handlers.

There are currently three types of DAX 4k entries: 4k zero pages, 4k DAX
mappings that have an associated block allocation, and 4k DAX empty
entries.  The empty entries exist to provide locking for the duration of a
given page fault.

This patch adds three equivalent 2MiB DAX entries: Huge Zero Page (HZP)
entries, PMD DAX entries that have associated block allocations, and 2 MiB
DAX empty entries.

Unlike the 4k case where we insert a struct page* into the radix tree for
4k zero pages, for HZP we insert a DAX exceptional entry with the new
RADIX_DAX_HZP flag set.  This is because we use a single 2 MiB zero page in
every 2MiB hole mapping, and it doesn't make sense to have that same struct
page* with multiple entries in multiple trees.  This would cause contention
on the single page lock for the one Huge Zero Page, and it would break the
page->index and page->mapping associations that are assumed to be valid in
many other places in the kernel.

One difficult use case is when one thread is trying to use 4k entries in
radix tree for a given offset, and another thread is using 2 MiB entries
for that same offset.  The current code handles this by making the 2 MiB
user fall back to 4k entries for most cases.  This was done because it is
the simplest solution, and because the use of 2MiB pages is already
opportunistic.

If we were to try to upgrade from 4k pages to 2MiB pages for a given range,
we run into the problem of how we lock out 4k page faults for the entire
2MiB range while we clean out the radix tree so we can insert the 2MiB
entry.  We can solve this problem if we need to, but I think that the cases
where both 2MiB entries and 4K entries are being used for the same range
will be rare enough and the gain small enough that it probably won't be
worth the complexity.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <david@fromorbit.com>
 		2016-11-08 11:34:45 +11:00
..
kasan kasan: remove the unnecessary WARN_ONCE from quarantine.c 2016-08-11 16:58:14 -07:00
Kconfig mm: clarify COMPACTION Kconfig text 2016-08-26 17:39:35 -07:00
Kconfig.debug PM / Hibernate: allow hibernation with PAGE_POISONING_ZERO 2016-09-13 02:35:27 +02:00
Makefile Disable the __builtin_return_address() warning globally after all 2016-10-12 10:23:41 -07:00
backing-dev.c block: fix bdi vs gendisk lifetime mismatch 2016-08-04 14:19:16 -06:00
balloon_compaction.c mm: balloon: use general non-lru movable page feature 2016-07-26 16:19:19 -07:00
bootmem.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
cleancache.c cleancache: constify cleancache_ops structure 2016-01-27 09:09:57 -05:00
cma.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
cma.h mm: cma: mark cma_bitmap_maxno() inline in header 2015-08-14 15:56:32 -07:00
cma_debug.c mm/cma_debug: correct size input to bitmap function 2015-07-17 16:39:54 -07:00
compaction.c mm, compaction: restrict fragindex to costly orders 2016-10-07 18:46:29 -07:00
debug.c mm: clarify why we avoid page_mapcount() for slab pages in dump_page() 2016-10-07 18:46:29 -07:00
debug_page_ref.c mm/page_ref: add tracepoint to track down page reference manipulation 2016-03-17 15:09:34 -07:00
dmapool.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
early_ioremap.c mm/early_ioremap: use offset_in_page macro 2015-11-05 19:34:48 -08:00
fadvise.c mm/fadvise.c: do not discard partial pages with POSIX_FADV_DONTNEED 2016-06-09 14:23:11 -07:00
failslab.c mm: fault-inject take over bootstrap kmem_cache check 2016-03-15 16:55:16 -07:00
filemap.c dax: add struct iomap based DAX PMD support 2016-11-08 11:34:45 +11:00
frame_vector.c mm/gup: Switch all callers of get_user_pages() to not pass tsk/mm 2016-02-16 10:11:12 +01:00
frontswap.c mm, frontswap: convert frontswap_enabled to static key 2016-07-26 16:19:19 -07:00
gup.c - ARM: GICv3 ITS emulation and various fixes. Removal of the old 2016-08-02 16:11:27 -04:00
highmem.c mm/highmem: make nr_free_highpages() handles all highmem zones by itself 2016-05-19 19:12:14 -07:00
huge_memory.c mm: vm_page_prot: update with WRITE_ONCE/READ_ONCE 2016-10-07 18:46:29 -07:00
hugetlb.c mm: remove unnecessary condition in remove_inode_hugepages 2016-10-07 18:46:29 -07:00
hugetlb_cgroup.c mm, hugetlb_cgroup: round limit_in_bytes down to hugepage size 2016-05-20 17:58:30 -07:00
hwpoison-inject.c hwpoison: use page_cgroup_ino for filtering by memcg 2015-09-10 13:29:01 -07:00
init-mm.c
…
internal.h mm, compaction: make full priority ignore pageblock suitability 2016-10-07 18:46:29 -07:00
interval_tree.c mm: replace vma->sharead.linear with vma->shared 2015-02-10 14:30:31 -08:00
khugepaged.c mm, thp: fix leaking mapped pte in __collapse_huge_page_swapin() 2016-09-19 15:36:16 -07:00
kmemcheck.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak-test.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
kmemleak.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
ksm.c mm,ksm: add __GFP_HIGH to the allocation in alloc_stable_node() 2016-10-07 18:46:29 -07:00
list_lru.c mm: memcontrol: move kmem accounting code to CONFIG_MEMCG 2016-01-20 17:09:18 -08:00
maccess.c x86: remove more uaccess_32.h complexity 2016-05-22 17:21:27 -07:00
madvise.c mm: make mmap_sem for write waits killable for mm syscalls 2016-05-23 17:04:14 -07:00
memblock.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
memcontrol.c mm: memcontrol: consolidate cgroup socket tracking 2016-10-07 18:46:29 -07:00
memory-failure.c mm: hwpoison: remove incorrect comments 2016-07-28 16:07:41 -07:00
memory.c mm: fix cache mode tracking in vm_insert_mixed() 2016-10-07 18:46:28 -07:00
memory_hotplug.c mm/hugetlb: check for reserved hugepages during memory offline 2016-10-07 18:46:29 -07:00
mempolicy.c mm: use zonelist name instead of using hardcoded index 2016-10-07 18:46:28 -07:00
mempool.c Revert "mm, mempool: only set __GFP_NOMEMALLOC if there are free elements" 2016-07-28 16:07:41 -07:00
memtest.c memtest: remove unused header files 2015-09-08 15:35:28 -07:00
migrate.c mm: vm_page_prot: update with WRITE_ONCE/READ_ONCE 2016-10-07 18:46:29 -07:00
mincore.c mm, swap: use offset of swap entry as key of swap cache 2016-10-07 18:46:28 -07:00
mlock.c mm: mlock: avoid increase mm->locked_vm on mlock() when already mlock2(,MLOCK_ONFAULT) 2016-10-07 18:46:28 -07:00
mm_init.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
mmap.c mm: vma_merge: correct false positive from __vma_unlink->validate_mm_rb 2016-10-07 18:46:29 -07:00
mmu_context.c mm/mmu_context, sched/core: Fix mmu_context.h assumption 2016-04-28 11:44:19 +02:00
mmu_notifier.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
mmzone.c mm, page_alloc: inline the fast path of the zonelist iterator 2016-05-19 19:12:14 -07:00
mprotect.c Merge branch 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-10 11:01:51 -07:00
mremap.c mm: thp: check pmd_trans_unstable() after split_huge_pmd() 2016-07-26 16:19:19 -07:00
msync.c mm/msync: use offset_in_page macro 2015-11-05 19:34:48 -08:00
nobootmem.c mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping 2016-10-11 15:06:33 -07:00
nommu.c mm: introduce fault_env 2016-07-26 16:19:19 -07:00
oom_kill.c oom: print nodemask in the oom report 2016-10-07 18:46:29 -07:00
page-writeback.c mm: don't use radix tree writeback tags for pages in swap cache 2016-10-07 18:46:28 -07:00
page_alloc.c This adds a new gcc plugin named "latent_entropy". It is designed to 2016-10-15 10:03:15 -07:00
page_counter.c mm: page_counter: let page_counter_try_charge() return bool 2015-11-05 19:34:48 -08:00
page_ext.c mm/page_ext: support extra space allocation by page_ext user 2016-10-07 18:46:27 -07:00
page_idle.c mm, vmscan: move lru_lock to the node 2016-07-28 16:07:41 -07:00
page_io.c mm/page_io.c: replace some BUG_ON()s with VM_BUG_ON_PAGE() 2016-10-07 18:46:29 -07:00
page_isolation.c mm/page_isolation: fix typo: "paes" -> "pages" 2016-10-07 18:46:29 -07:00
page_owner.c mm/page_owner: don't define fields on struct page_ext by hard-coding 2016-10-07 18:46:27 -07:00
page_poison.c mm: check the return value of lookup_page_ext for all call sites 2016-06-03 15:06:22 -07:00
pagewalk.c thp: rename split_huge_page_pmd() to split_huge_pmd() 2016-01-15 17:56:32 -08:00
percpu-km.c mm: percpu: use pr_fmt to prefix output 2016-03-17 15:09:34 -07:00
percpu-vm.c percpu: move region iterations out of pcpu_[de]populate_chunk() 2014-09-02 14:46:02 -04:00
percpu.c mm/percpu.c: fix potential memory leakage for pcpu_embed_first_chunk() 2016-10-05 11:52:55 -04:00
pgtable-generic.c mm/thp/migration: switch from flush_tlb_range to flush_pmd_tlb_range 2016-03-17 15:09:34 -07:00
process_vm_access.c mm/gup: Introduce get_user_pages_remote() 2016-02-16 10:04:09 +01:00
quicklist.c fix Christoph's email addresses 2016-03-17 15:09:34 -07:00
readahead.c mm: silently skip readahead for DAX inodes 2016-08-26 17:39:35 -07:00
rmap.c rmap: fix compound check logic in page_remove_file_rmap 2016-08-10 16:40:56 -07:00
shmem.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-10-10 20:16:43 -07:00
slab.c slab: Convert to hotplug state machine 2016-09-06 18:30:20 +02:00
slab.h mm, kasan: switch SLUB to stackdepot, enable memory quarantine for SLUB 2016-07-28 16:07:41 -07:00
slab_common.c mm: charge/uncharge kmemcg from generic page allocator paths 2016-07-26 16:19:19 -07:00
slob.c mm: slab: free kmem_cache_node after destroy sysfs file 2016-02-18 16:23:24 -08:00
slub.c slub: Convert to hotplug state machine 2016-09-06 18:30:20 +02:00
sparse-vmemmap.c treewide: replace obsolete _refok by __ref 2016-08-02 17:31:41 -04:00
sparse.c treewide: replace obsolete _refok by __ref 2016-08-02 17:31:41 -04:00
swap.c thp: reduce usage of huge zero page's atomic counter 2016-10-07 18:46:28 -07:00
swap_cgroup.c mm: convert printk(KERN_<LEVEL> to pr_<level> 2016-03-17 15:09:34 -07:00
swap_state.c mm, swap: use offset of swap entry as key of swap cache 2016-10-07 18:46:28 -07:00
swapfile.c mm, swap: use offset of swap entry as key of swap cache 2016-10-07 18:46:28 -07:00
truncate.c truncate: handle file thp 2016-07-26 16:19:19 -07:00
usercopy.c mm: usercopy: Check for module addresses 2016-09-20 16:07:39 -07:00
userfaultfd.c mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros 2016-04-04 10:41:08 -07:00
util.c mm: move most file-based accounting to the node 2016-07-28 16:07:41 -07:00
vmacache.c mm: unrig VMA cache hit ratio 2016-10-07 18:46:27 -07:00
vmalloc.c mm: consolidate warn_alloc_failed users 2016-10-07 18:46:29 -07:00
vmpressure.c mm/vmpressure.c: fix subtree pressure detection 2016-02-03 08:28:43 -08:00
vmscan.c mm: use zonelist name instead of using hardcoded index 2016-10-07 18:46:28 -07:00
vmstat.c seq/proc: modify seq_put_decimal_[u]ll to take a const char *, not char 2016-10-07 18:46:30 -07:00
workingset.c mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page() 2016-09-30 15:26:52 -07:00
z3fold.c mm/z3fold.c: avoid modifying HEADLESS page and minor cleanup 2016-06-03 16:02:55 -07:00
zbud.c mm/zbud.c: use list_last_entry() instead of list_tail_entry() 2016-01-15 11:40:52 -08:00
zpool.c mm: zsmalloc: constify struct zs_pool name 2015-11-06 17:50:42 -08:00
zsmalloc.c zsmalloc: Delete an unnecessary check before the function call "iput" 2016-07-28 16:07:41 -07:00
zswap.c mm/zswap: use workqueue to destroy pool 2016-05-20 17:58:30 -07:00