1. 06 Jul, 2019 1 commit
    • Linus Torvalds's avatar
      Revert "mm: page cache: store only head pages in i_pages" · 69bf4b6b
      Linus Torvalds authored
      This reverts commit 5fd4ca2d.
      
      Mikhail Gavrilov reports that it causes the VM_BUG_ON_PAGE() in
      __delete_from_swap_cache() to trigger:
      
         page:ffffd6d34dff0000 refcount:1 mapcount:1 mapping:ffff97812323a689 index:0xfecec363
         anon
         flags: 0x17fffe00080034(uptodate|lru|active|swapbacked)
         raw: 0017fffe00080034 ffffd6d34c67c508 ffffd6d3504b8d48 ffff97812323a689
         raw: 00000000fecec363 0000000000000000 0000000100000000 ffff978433ace000
         page dumped because: VM_BUG_ON_PAGE(entry != page)
         page->mem_cgroup:ffff978433ace000
         ------------[ cut here ]------------
         kernel BUG at mm/swap_state.c:170!
         invalid opcode: 0000 [#1] SMP NOPTI
         CPU: 1 PID: 221 Comm: kswapd0 Not tainted 5.2.0-0.rc2.git0.1.fc31.x86_64 #1
         Hardware name: System manufacturer System Product Name/ROG STRIX X470-I GAMING, BIOS 2202 04/11/2019
         RIP: 0010:__delete_from_swap_cache+0x20d/0x240
         Code: 30 65 48 33 04 25 28 00 00 00 75 4a 48 83 c4 38 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 c7 c6 2f dc 0f 8a 48 89 c7 e8 93 1b fd ff <0f> 0b 48 c7 c6 a8 74 0f 8a e8 85 1b fd ff 0f 0b 48 c7 c6 a8 7d 0f
         RSP: 0018:ffffa982036e7980 EFLAGS: 00010046
         RAX: 0000000000000021 RBX: 0000000000000040 RCX: 0000000000000006
         RDX: 0000000000000000 RSI: 0000000000000086 RDI: ffff97843d657900
         RBP: 0000000000000001 R08: ffffa982036e7835 R09: 0000000000000535
         R10: ffff97845e21a46c R11: ffffa982036e7835 R12: ffff978426387120
         R13: 0000000000000000 R14: ffffd6d34dff0040 R15: ffffd6d34dff0000
         FS:  0000000000000000(0000) GS:ffff97843d640000(0000) knlGS:0000000000000000
         CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
         CR2: 00002cba88ef5000 CR3: 000000078a97c000 CR4: 00000000003406e0
         Call Trace:
          delete_from_swap_cache+0x46/0xa0
          try_to_free_swap+0xbc/0x110
          swap_writepage+0x13/0x70
          pageout.isra.0+0x13c/0x350
          shrink_page_list+0xc14/0xdf0
          shrink_inactive_list+0x1e5/0x3c0
          shrink_node_memcg+0x202/0x760
          shrink_node+0xe0/0x470
          balance_pgdat+0x2d1/0x510
          kswapd+0x220/0x420
          kthread+0xfb/0x130
          ret_from_fork+0x22/0x40
      
      and it's not immediately obvious why it happens.  It's too late in the
      rc cycle to do anything but revert for now.
      
      Link: https://lore.kernel.org/lkml/CABXGCsN9mYmBD-4GaaeW_NrDu+FDXLzr_6x+XNxfmFV6QkYCDg@mail.gmail.com/Reported-and-bisected-by: default avatarMikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
      Suggested-by: default avatarJan Kara <jack@suse.cz>
      Cc: Michal Hocko <mhocko@kernel.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Matthew Wilcox <willy@infradead.org>
      Cc: Kirill Shutemov <kirill@shutemov.name>
      Cc: William Kucharski <william.kucharski@oracle.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      69bf4b6b
  2. 14 May, 2019 1 commit
  3. 06 Mar, 2019 1 commit
    • Joel Fernandes (Google)'s avatar
      mm/memfd: add an F_SEAL_FUTURE_WRITE seal to memfd · ab3948f5
      Joel Fernandes (Google) authored
      Android uses ashmem for sharing memory regions.  We are looking forward
      to migrating all usecases of ashmem to memfd so that we can possibly
      remove the ashmem driver in the future from staging while also
      benefiting from using memfd and contributing to it.  Note staging
      drivers are also not ABI and generally can be removed at anytime.
      
      One of the main usecases Android has is the ability to create a region
      and mmap it as writeable, then add protection against making any
      "future" writes while keeping the existing already mmap'ed
      writeable-region active.  This allows us to implement a usecase where
      receivers of the shared memory buffer can get a read-only view, while
      the sender continues to write to the buffer.  See CursorWindow
      documentation in Android for more details:
      
        https://developer.android.com/reference/android/database/CursorWindow
      
      This usecase cannot be implemented with the existing F_SEAL_WRITE seal.
      To support the usecase, this patch adds a new F_SEAL_FUTURE_WRITE seal
      which prevents any future mmap and write syscalls from succeeding while
      keeping the existing mmap active.
      
      A better way to do F_SEAL_FUTURE_WRITE seal was discussed [1] last week
      where we don't need to modify core VFS structures to get the same
      behavior of the seal.  This solves several side-effects pointed by Andy.
      self-tests are provided in later patch to verify the expected semantics.
      
      [1] https://lore.kernel.org/lkml/20181111173650.GA256781@google.com/
      
      Thanks a lot to Andy for suggestions to improve code.
      
      Link: http://lkml.kernel.org/r/20190112203816.85534-2-joel@joelfernandes.orgSigned-off-by: default avatarJoel Fernandes (Google) <joel@joelfernandes.org>
      Acked-by: default avatarJohn Stultz <john.stultz@linaro.org>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Jann Horn <jannh@google.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: Andy Lutomirski <luto@kernel.org>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: J. Bruce Fields <bfields@fieldses.org>
      Cc: Jeff Layton <jlayton@kernel.org>
      Cc: Marc-Andr Lureau <marcandre.lureau@redhat.com>
      Cc: Matthew Wilcox <willy@infradead.org>
      Cc: Mike Kravetz <mike.kravetz@oracle.com>
      Cc: Shuah Khan <shuah@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ab3948f5
  4. 21 Oct, 2018 2 commits
  5. 12 Jul, 2018 1 commit
  6. 08 Jun, 2018 1 commit
    • Mike Kravetz's avatar
      mm: restructure memfd code · 5d752600
      Mike Kravetz authored
      With the addition of memfd hugetlbfs support, we now have the situation
      where memfd depends on TMPFS -or- HUGETLBFS.  Previously, memfd was only
      supported on tmpfs, so it made sense that the code resided in shmem.c.
      In the current code, memfd is only functional if TMPFS is defined.  If
      HUGETLFS is defined and TMPFS is not defined, then memfd functionality
      will not be available for hugetlbfs.  This does not cause BUGs, just a
      lack of potentially desired functionality.
      
      Code is restructured in the following way:
      - include/linux/memfd.h is a new file containing memfd specific
        definitions previously contained in shmem_fs.h.
      - mm/memfd.c is a new file containing memfd specific code previously
        contained in shmem.c.
      - memfd specific code is removed from shmem_fs.h and shmem.c.
      - A new config option MEMFD_CREATE is added that is defined if TMPFS
        or HUGETLBFS is defined.
      
      No functional changes are made to the code: restructuring only.
      
      Link: http://lkml.kernel.org/r/20180415182119.4517-4-mike.kravetz@oracle.comSigned-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
      Reviewed-by: default avatarKhalid Aziz <khalid.aziz@oracle.com>
      Cc: Andrea Arcangeli <aarcange@redhat.com>
      Cc: David Herrmann <dh.herrmann@gmail.com>
      Cc: Hugh Dickins <hughd@google.com>
      Cc: Marc-Andr Lureau <marcandre.lureau@gmail.com>
      Cc: Matthew Wilcox <willy@infradead.org>
      Cc: Michal Hocko <mhocko@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      5d752600