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timer_callback() runs in softirq context and acquires recinf->lock, but the process-context callers (scoutfs_recov_prepare, _begin, _finish, _is_pending, _next_pending, _shutdown) were taking the same lock with plain spin_lock(), leaving softirqs enabled. Found by Lockdep: ``` ================================ WARNING: inconsistent lock state 5.14.0-427.35.1.el9_4.x86_64+debug #1 Tainted: G OE ------- --- -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/2/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff88813cdd9c20 (&recinf->lock){+.?.}-{2:2}, at: timer_callback+0x26/0x380 [scoutfs] {SOFTIRQ-ON-W} state was registered at: __lock_acquire+0x7d0/0x1900 lock_acquire+0x1da/0x640 _raw_spin_lock+0x34/0x80 scoutfs_recov_finish+0x80/0x830 [scoutfs] server_greeting+0x244/0xe60 [scoutfs] scoutfs_net_proc_worker+0x28a/0xce0 [scoutfs] recv_one_message+0x7e3/0xd10 [scoutfs] scoutfs_net_recv_worker+0x441/0xe00 [scoutfs] process_one_work+0x8e5/0x1530 worker_thread+0x598/0xf70 kthread+0x2a4/0x350 ret_from_fork+0x29/0x50 irq event stamp: 549813370 hardirqs last enabled at (549813370): [<ffffffffabe25cb4>] _raw_spin_unlock_irq+0x24/0x50 hardirqs last disabled at (549813369): [<ffffffffabe2594e>] _raw_spin_lock_irq+0x5e/0x90 softirqs last enabled at (549813356): [<ffffffffabe28c91>] __do_softirq+0x621/0x9c2 softirqs last disabled at (549813363): [<ffffffffa9a44665>] __irq_exit_rcu+0x185/0x230 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&recinf->lock); <Interrupt> lock(&recinf->lock); *** DEADLOCK *** ``` Convert the six process-context sites to spin_lock_bh()/spin_unlock_bh(). Signed-off-by: Auke Kok <auke.kok@versity.com>
Introduction
scoutfs is a clustered in-kernel Linux filesystem designed to support large archival systems. It features additional interfaces and metadata so that archive agents can perform their maintenance workflows without walking all the files in the namespace. Its cluster support lets deployments add nodes to satisfy archival tier bandwidth targets.
The design goal is to reach file populations in the trillions, with the archival bandwidth to match, while remaining operational and responsive.
Highlights of the design and implementation include:
- Fully consistent POSIX semantics between nodes
- Atomic transactions to maintain consistent persistent structures
- Integrated archival metadata replaces syncing to external databases
- Dynamic seperation of resources lets nodes write in parallel
- 64bit throughout; no limits on file or directory sizes or counts
- Open GPLv2 implementation
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