• Suren Baghdasaryan's avatar
    mm: enable page walking API to lock vmas during the walk · 49b06385
    Suren Baghdasaryan authored
    walk_page_range() and friends often operate under write-locked mmap_lock. 
    With introduction of vma locks, the vmas have to be locked as well during
    such walks to prevent concurrent page faults in these areas.  Add an
    additional member to mm_walk_ops to indicate locking requirements for the
    walk.
    
    The change ensures that page walks which prevent concurrent page faults
    by write-locking mmap_lock, operate correctly after introduction of
    per-vma locks.  With per-vma locks page faults can be handled under vma
    lock without taking mmap_lock at all, so write locking mmap_lock would
    not stop them.  The change ensures vmas are properly locked during such
    walks.
    
    A sample issue this solves is do_mbind() performing queue_pages_range()
    to queue pages for migration.  Without this change a concurrent page
    can be faulted into the area and be left out of migration.
    
    Link: https://lkml.kernel.org/r/20230804152724.3090321-2-surenb@google.comSigned-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
    Suggested-by: default avatarLinus Torvalds <torvalds@linuxfoundation.org>
    Suggested-by: default avatarJann Horn <jannh@google.com>
    Cc: David Hildenbrand <david@redhat.com>
    Cc: Davidlohr Bueso <dave@stgolabs.net>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Cc: Laurent Dufour <ldufour@linux.ibm.com>
    Cc: Liam Howlett <liam.howlett@oracle.com>
    Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
    Cc: Michal Hocko <mhocko@suse.com>
    Cc: Michel Lespinasse <michel@lespinasse.org>
    Cc: Peter Xu <peterx@redhat.com>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    49b06385
task_mmu.c 49.2 KB