lkml.org 
[lkml]   [2020]   [Dec]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.10 377/717] nfs_common: need lock during iterate through the list
    Date
    From: Cheng Lin <cheng.lin130@zte.com.cn>

    [ Upstream commit 4a9d81caf841cd2c0ae36abec9c2963bf21d0284 ]

    If the elem is deleted during be iterated on it, the iteration
    process will fall into an endless loop.

    kernel: NMI watchdog: BUG: soft lockup - CPU#4 stuck for 22s! [nfsd:17137]

    PID: 17137  TASK: ffff8818d93c0000  CPU: 4   COMMAND: "nfsd"
        [exception RIP: __state_in_grace+76]
        RIP: ffffffffc00e817c  RSP: ffff8818d3aefc98  RFLAGS: 00000246
        RAX: ffff881dc0c38298  RBX: ffffffff81b03580  RCX: ffff881dc02c9f50
        RDX: ffff881e3fce8500  RSI: 0000000000000001  RDI: ffffffff81b03580
        RBP: ffff8818d3aefca0   R8: 0000000000000020   R9: ffff8818d3aefd40
        R10: ffff88017fc03800  R11: ffff8818e83933c0  R12: ffff8818d3aefd40
        R13: 0000000000000000  R14: ffff8818e8391068  R15: ffff8818fa6e4000
        CS: 0010  SS: 0018
     #0 [ffff8818d3aefc98] opens_in_grace at ffffffffc00e81e3 [grace]
     #1 [ffff8818d3aefca8] nfs4_preprocess_stateid_op at ffffffffc02a3e6c [nfsd]
     #2 [ffff8818d3aefd18] nfsd4_write at ffffffffc028ed5b [nfsd]
     #3 [ffff8818d3aefd80] nfsd4_proc_compound at ffffffffc0290a0d [nfsd]
     #4 [ffff8818d3aefdd0] nfsd_dispatch at ffffffffc027b800 [nfsd]
     #5 [ffff8818d3aefe08] svc_process_common at ffffffffc02017f3 [sunrpc]
     #6 [ffff8818d3aefe70] svc_process at ffffffffc0201ce3 [sunrpc]
     #7 [ffff8818d3aefe98] nfsd at ffffffffc027b117 [nfsd]
     #8 [ffff8818d3aefec8] kthread at ffffffff810b88c1
     #9 [ffff8818d3aeff50] ret_from_fork at ffffffff816d1607

    The troublemake elem:
    crash> lock_manager ffff881dc0c38298
    struct lock_manager {
      list = {
        next = 0xffff881dc0c38298,
        prev = 0xffff881dc0c38298
      },
      block_opens = false
    }

    Fixes: c87fb4a378f9 ("lockd: NLM grace period shouldn't block NFSv4 opens")
    Signed-off-by: Cheng Lin <cheng.lin130@zte.com.cn>
    Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
    Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    fs/nfs_common/grace.c | 6 +++++-
    1 file changed, 5 insertions(+), 1 deletion(-)

    diff --git a/fs/nfs_common/grace.c b/fs/nfs_common/grace.c
    index b73d9dd37f73c..26f2a50eceac9 100644
    --- a/fs/nfs_common/grace.c
    +++ b/fs/nfs_common/grace.c
    @@ -69,10 +69,14 @@ __state_in_grace(struct net *net, bool open)
    if (!open)
    return !list_empty(grace_list);

    + spin_lock(&grace_lock);
    list_for_each_entry(lm, grace_list, list) {
    - if (lm->block_opens)
    + if (lm->block_opens) {
    + spin_unlock(&grace_lock);
    return true;
    + }
    }
    + spin_unlock(&grace_lock);
    return false;
    }

    --
    2.27.0


    \
     
     \ /
      Last update: 2020-12-28 15:40    [W:4.953 / U:2.376 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site