diff options
| author | Mike Kravetz <mike.kravetz@oracle.com> | 2019-01-08 15:23:36 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-01-08 17:15:11 -0800 |
| commit | ddeaab32a89f04b7e2a2df8771583a719c4ac6b7 (patch) | |
| tree | faa31cf72190bc24e3041c924da8e7d58d8c99f0 /mm/rmap.c | |
| parent | e7c58097793ef15d58fadf190ee58738fbf447cd (diff) | |
| download | lwn-ddeaab32a89f04b7e2a2df8771583a719c4ac6b7.tar.gz lwn-ddeaab32a89f04b7e2a2df8771583a719c4ac6b7.zip | |
hugetlbfs: revert "use i_mmap_rwsem for more pmd sharing synchronization"
This reverts b43a9990055958e70347c56f90ea2ae32c67334c
The reverted commit caused issues with migration and poisoning of anon
huge pages. The LTP move_pages12 test will cause an "unable to handle
kernel NULL pointer" BUG would occur with stack similar to:
RIP: 0010:down_write+0x1b/0x40
Call Trace:
migrate_pages+0x81f/0xb90
__ia32_compat_sys_migrate_pages+0x190/0x190
do_move_pages_to_node.isra.53.part.54+0x2a/0x50
kernel_move_pages+0x566/0x7b0
__x64_sys_move_pages+0x24/0x30
do_syscall_64+0x5b/0x180
entry_SYSCALL_64_after_hwframe+0x44/0xa9
The purpose of the reverted patch was to fix some long existing races
with huge pmd sharing. It used i_mmap_rwsem for this purpose with the
idea that this could also be used to address truncate/page fault races
with another patch. Further analysis has determined that i_mmap_rwsem
can not be used to address all these hugetlbfs synchronization issues.
Therefore, revert this patch while working an another approach to the
underlying issues.
Link: http://lkml.kernel.org/r/20190103235452.29335-2-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: Jan Stancek <jstancek@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Prakash Sangappa <prakash.sangappa@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 21a26cf51114..68a1a5b869a5 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -25,7 +25,6 @@ * page->flags PG_locked (lock_page) * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share) * mapping->i_mmap_rwsem - * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) * anon_vma->rwsem * mm->page_table_lock or pte_lock * zone_lru_lock (in mark_page_accessed, isolate_lru_page) @@ -1379,9 +1378,6 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, /* * If sharing is possible, start and end will be adjusted * accordingly. - * - * If called for a huge page, caller must hold i_mmap_rwsem - * in write mode as it is possible to call huge_pmd_unshare. */ adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end); |