• Kefeng Wang's avatar
    mm: hwpoison: coredump: support recovery from dump_user_range() · 245f0922
    Kefeng Wang authored
    dump_user_range() is used to copy the user page to a coredump file, but if
    a hardware memory error occurred during copy, which called from
    __kernel_write_iter() in dump_user_range(), it crashes,
    
      CPU: 112 PID: 7014 Comm: mca-recover Not tainted 6.3.0-rc2 #425
    
      pc : __memcpy+0x110/0x260
      lr : _copy_from_iter+0x3bc/0x4c8
      ...
      Call trace:
       __memcpy+0x110/0x260
       copy_page_from_iter+0xcc/0x130
       pipe_write+0x164/0x6d8
       __kernel_write_iter+0x9c/0x210
       dump_user_range+0xc8/0x1d8
       elf_core_dump+0x308/0x368
       do_coredump+0x2e8/0xa40
       get_signal+0x59c/0x788
       do_signal+0x118/0x1f8
       do_notify_resume+0xf0/0x280
       el0_da+0x130/0x138
       el0t_64_sync_handler+0x68/0xc0
       el0t_64_sync+0x188/0x190
    
    Generally, the '->write_iter' of file ops will use copy_page_from_iter()
    and copy_page_from_iter_atomic(), change memcpy() to copy_mc_to_kernel()
    in both of them to handle #MC during source read, which stop coredump
    processing and kill the task instead of kernel panic, but the source
    address may not always a user address, so introduce a new copy_mc flag in
    struct iov_iter{} to indicate that the iter could do a safe memory copy,
    also introduce the helpers to set/cleck the flag, for now, it's only used
    in coredump's dump_user_range(), but it could expand to any other
    scenarios to fix the similar issue.
    
    Link: https://lkml.kernel.org/r/20230417045323.11054-1-wangkefeng.wang@huawei.comSigned-off-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
    Cc: Alexander Viro <viro@zeniv.linux.org.uk>
    Cc: Christian Brauner <brauner@kernel.org>
    Cc: Miaohe Lin <linmiaohe@huawei.com>
    Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
    Cc: Tong Tiangen <tongtiangen@huawei.com>
    Cc: Jens Axboe <axboe@kernel.dk>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    245f0922
coredump.c 29.3 KB