diff options
author | Jann Horn <jannh@google.com> | 2020-10-15 20:12:57 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-10-16 11:11:21 -0700 |
commit | 7f3bfab52cab96c510fd60dd757a32db7bc52d3c (patch) | |
tree | 56a0c274000eac4b997a2fbc1d9bc044270c3c54 /mm/gup.c | |
parent | a07279c9a8cd7dbd321640ff7210591599ee00a4 (diff) |
mm/gup: take mmap_lock in get_dump_page()
Properly take the mmap_lock before calling into the GUP code from
get_dump_page(); and play nice, allowing the GUP code to drop the
mmap_lock if it has to sleep.
As Linus pointed out, we don't actually need the VMA because
__get_user_pages() will flush the dcache for us if necessary.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200827114932.3572699-7-jannh@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r-- | mm/gup.c | 16 |
1 files changed, 10 insertions, 6 deletions
@@ -1547,19 +1547,23 @@ finish_or_fault: * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - * allowing a hole to be left in the corefile to save diskspace. * - * Called without mmap_lock, but after all other threads have been killed. + * Called without mmap_lock (takes and releases the mmap_lock by itself). */ #ifdef CONFIG_ELF_CORE struct page *get_dump_page(unsigned long addr) { - struct vm_area_struct *vma; + struct mm_struct *mm = current->mm; struct page *page; + int locked = 1; + int ret; - if (__get_user_pages_locked(current->mm, addr, 1, &page, &vma, NULL, - FOLL_FORCE | FOLL_DUMP | FOLL_GET) < 1) + if (mmap_read_lock_killable(mm)) return NULL; - flush_cache_page(vma, addr, page_to_pfn(page)); - return page; + ret = __get_user_pages_locked(mm, addr, 1, &page, NULL, &locked, + FOLL_FORCE | FOLL_DUMP | FOLL_GET); + if (locked) + mmap_read_unlock(mm); + return (ret == 1) ? page : NULL; } #endif /* CONFIG_ELF_CORE */ |