• J. Bruce Fields's avatar
    nfsd4: make drc_slab global, not per-net · 027690c7
    J. Bruce Fields authored
    I made every global per-network-namespace instead.  But perhaps doing
    that to this slab was a step too far.
    
    The kmem_cache_create call in our net init method also seems to be
    responsible for this lockdep warning:
    
    [   45.163710] Unable to find swap-space signature
    [   45.375718] trinity-c1 (855): attempted to duplicate a private mapping with mremap.  This is not supported.
    [   46.055744] futex_wake_op: trinity-c1 tries to shift op by -209; fix this program
    [   51.011723]
    [   51.013378] ======================================================
    [   51.013875] WARNING: possible circular locking dependency detected
    [   51.014378] 5.2.0-rc2 #1 Not tainted
    [   51.014672] ------------------------------------------------------
    [   51.015182] trinity-c2/886 is trying to acquire lock:
    [   51.015593] 000000005405f099 (slab_mutex){+.+.}, at: slab_attr_store+0xa2/0x130
    [   51.016190]
    [   51.016190] but task is already holding lock:
    [   51.016652] 00000000ac662005 (kn->count#43){++++}, at: kernfs_fop_write+0x286/0x500
    [   51.017266]
    [   51.017266] which lock already depends on the new lock.
    [   51.017266]
    [   51.017909]
    [   51.017909] the existing dependency chain (in reverse order) is:
    [   51.018497]
    [   51.018497] -> #1 (kn->count#43){++++}:
    [   51.018956]        __lock_acquire+0x7cf/0x1a20
    [   51.019317]        lock_acquire+0x17d/0x390
    [   51.019658]        __kernfs_remove+0x892/0xae0
    [   51.020020]        kernfs_remove_by_name_ns+0x78/0x110
    [   51.020435]        sysfs_remove_link+0x55/0xb0
    [   51.020832]        sysfs_slab_add+0xc1/0x3e0
    [   51.021332]        __kmem_cache_create+0x155/0x200
    [   51.021720]        create_cache+0xf5/0x320
    [   51.022054]        kmem_cache_create_usercopy+0x179/0x320
    [   51.022486]        kmem_cache_create+0x1a/0x30
    [   51.022867]        nfsd_reply_cache_init+0x278/0x560
    [   51.023266]        nfsd_init_net+0x20f/0x5e0
    [   51.023623]        ops_init+0xcb/0x4b0
    [   51.023928]        setup_net+0x2fe/0x670
    [   51.024315]        copy_net_ns+0x30a/0x3f0
    [   51.024653]        create_new_namespaces+0x3c5/0x820
    [   51.025257]        unshare_nsproxy_namespaces+0xd1/0x240
    [   51.025881]        ksys_unshare+0x506/0x9c0
    [   51.026381]        __x64_sys_unshare+0x3a/0x50
    [   51.026937]        do_syscall_64+0x110/0x10b0
    [   51.027509]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [   51.028175]
    [   51.028175] -> #0 (slab_mutex){+.+.}:
    [   51.028817]        validate_chain+0x1c51/0x2cc0
    [   51.029422]        __lock_acquire+0x7cf/0x1a20
    [   51.029947]        lock_acquire+0x17d/0x390
    [   51.030438]        __mutex_lock+0x100/0xfa0
    [   51.030995]        mutex_lock_nested+0x27/0x30
    [   51.031516]        slab_attr_store+0xa2/0x130
    [   51.032020]        sysfs_kf_write+0x11d/0x180
    [   51.032529]        kernfs_fop_write+0x32a/0x500
    [   51.033056]        do_loop_readv_writev+0x21d/0x310
    [   51.033627]        do_iter_write+0x2e5/0x380
    [   51.034148]        vfs_writev+0x170/0x310
    [   51.034616]        do_pwritev+0x13e/0x160
    [   51.035100]        __x64_sys_pwritev+0xa3/0x110
    [   51.035633]        do_syscall_64+0x110/0x10b0
    [   51.036200]        entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [   51.036924]
    [   51.036924] other info that might help us debug this:
    [   51.036924]
    [   51.037876]  Possible unsafe locking scenario:
    [   51.037876]
    [   51.038556]        CPU0                    CPU1
    [   51.039130]        ----                    ----
    [   51.039676]   lock(kn->count#43);
    [   51.040084]                                lock(slab_mutex);
    [   51.040597]                                lock(kn->count#43);
    [   51.041062]   lock(slab_mutex);
    [   51.041320]
    [   51.041320]  *** DEADLOCK ***
    [   51.041320]
    [   51.041793] 3 locks held by trinity-c2/886:
    [   51.042128]  #0: 000000001f55e152 (sb_writers#5){.+.+}, at: vfs_writev+0x2b9/0x310
    [   51.042739]  #1: 00000000c7d6c034 (&of->mutex){+.+.}, at: kernfs_fop_write+0x25b/0x500
    [   51.043400]  #2: 00000000ac662005 (kn->count#43){++++}, at: kernfs_fop_write+0x286/0x500
    Reported-by: default avatarkernel test robot <lkp@intel.com>
    Fixes: 3ba75830 "drc containerization"
    Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
    027690c7
nfsctl.c 39.2 KB