On Fri, Aug 30, 2024 at 12:20:13PM +1000, NeilBrown wrote: > Following are revised versions of 6 patches from the v14 localio series. > > The issue addressed is net namespace refcounting. > > We don't want to keep a long-term counted reference in the client > because that prevents a server container from completely shutting down. > > So we avoid taking a reference at all and rely on the per-cpu reference > to the server being sufficient to keep the net-ns active. This involves > allowing the net-ns exit code to iterate all active clients and clear > their ->net pointers (which they need to find the per-cpu-refcount for > the nfs_serv). > > So: > - embed nfs_uuid_t in nfs_client. This provides a list_head that can > be used to find the client. It does add the actual uuid to nfs_client > so it is bigger than needed. If that is really a problem we can find > a fix. > > - When the nfs server confirms that the uuid is local, it moves the > nfs_uuid_t onto a per-net-ns list. > > - When the net-ns is shutting down - in a "pre_exit" handler, all these > nfS_uuid_t have their ->net cleared. There is an rcu_synchronize() > call between pre_exit() handlers and exit() handlers so and caller > that sees ->net as not NULL can safely check the ->counter > > - We now pass the nfs_uuid_t to nfsd_open_local_fh() so it can safely > look at ->net in a private rcu_read_lock() section. > > I have compile tested this code but nothing more. > > Thanks, > NeilBrown > > [PATCH 14/25] nfs_common: add NFS LOCALIO auxiliary protocol > [PATCH 15/25] nfs_common: introduce nfs_localio_ctx struct and > [PATCH 16/25] nfsd: add localio support > [PATCH 17/25] nfsd: implement server support for NFS_LOCALIO_PROGRAM > [PATCH 19/25] nfs: add localio support > [PATCH 23/25] nfs: implement client support for NFS_LOCALIO_PROGRAM Hey Neil, I attempted to test the kernel with your changes but it crashed with: [ 55.422564] list_add corruption. next is NULL. [ 55.423523] ------------[ cut here ]------------ [ 55.424423] kernel BUG at lib/list_debug.c:27! [ 55.425291] Oops: invalid opcode: 0000 [#1] PREEMPT SMP NOPTI [ 55.426367] CPU: 29 UID: 0 PID: 5251 Comm: nfsd Kdump: loaded Not tainted 6.11.0-rc4.snitm+ #147 [ 55.427991] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-4.module+el8.9.0+19570+14a90618 04/01/2014 [ 55.429697] RIP: 0010:__list_add_valid_or_report+0x55/0xa0 [ 55.430741] Code: 4c 39 cf 74 4f b8 01 00 00 00 5d c3 cc cc cc cc 48 c7 c7 98 1d a5 82 e8 d9 6d 93 ff 0f 0b 48 c7 c7 c0 1d a5 82 e8 cb 6d 93 ff <0f> 0b 4c 89 c1 48 c7 c7 e8 1d a5 82 e8 ba 6d 93 ff 0f 0b 48 89 d1 [ 55.434167] RSP: 0018:ffff8881441a7d50 EFLAGS: 00010296 [ 55.435141] RAX: 0000000000000022 RBX: ffff888107b50370 RCX: 0000000000000000 [ 55.436455] RDX: ffff888473caf800 RSI: ffff888473ca18c0 RDI: ffff888473ca18c0 [ 55.437770] RBP: ffff8881441a7d50 R08: 0000000000000022 R09: ffff8881441a7be8 [ 55.439098] R10: ffff8881441a7be0 R11: ffffffff8333f328 R12: ffff888107b50380 [ 55.440419] R13: ffff888103b15080 R14: ffff888107bb5d00 R15: 0000000000000000 [ 55.441737] FS: 0000000000000000(0000) GS:ffff888473c80000(0000) knlGS:0000000000000000 [ 55.443228] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 55.444297] CR2: 000055958fab3488 CR3: 000000010615e000 CR4: 0000000000350ef0 [ 55.445615] Call Trace: [ 55.446090] <TASK> [ 55.446498] ? show_regs+0x6d/0x80 [ 55.447149] ? die+0x3c/0xa0 [ 55.447698] ? do_trap+0xcf/0xf0 [ 55.448316] ? do_error_trap+0x75/0xa0 [ 55.449026] ? __list_add_valid_or_report+0x55/0xa0 [ 55.449938] ? exc_invalid_op+0x57/0x80 [ 55.450660] ? __list_add_valid_or_report+0x55/0xa0 [ 55.451646] ? asm_exc_invalid_op+0x1f/0x30 [ 55.452438] ? __list_add_valid_or_report+0x55/0xa0 [ 55.453355] nfs_uuid_is_local+0xba/0x110 [ 55.454115] localio_proc_uuid_is_local+0x64/0x80 [nfsd] [ 55.455145] nfsd_dispatch+0xc2/0x210 [nfsd] [ 55.455977] svc_process_common+0x2e6/0x6e0 [ 55.456761] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd] [ 55.457697] svc_process+0x13e/0x1e0 [ 55.458377] svc_recv+0x89e/0xa70 [ 55.459012] ? __pfx_nfsd+0x10/0x10 [nfsd] [ 55.459806] nfsd+0xa5/0x100 [nfsd] [ 55.460486] kthread+0xe5/0x120 [ 55.461090] ? __pfx_kthread+0x10/0x10 [ 55.461801] ret_from_fork+0x3d/0x60 [ 55.462476] ? __pfx_kthread+0x10/0x10 [ 55.463184] ret_from_fork_asm+0x1a/0x30 [ 55.463923] </TASK> I'll triple check my melding of your changes and mine in ~7 hours.. I may have missed something. Note this is _not_ with your other incremental patch (that uses __module_get) -- only because I didn't get to that yet. Mike
