027690c75e
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: kernel test robot <lkp@intel.com> Fixes: 3ba75830ce17 "drc containerization" Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.