kernel/linux.git/include/linux/sunrpc/sched.h, branch v6.6.132

SUNRPC: Prevent looping due to rpc_signal_task() races

2025-03-07T15:45:36+00:00

[ Upstream commit 5bbd6e863b15a85221e49b9bdb2d5d8f0bb91f3d ] If rpc_signal_task() is called while a task is in an rpc_call_done() callback function, and the latter calls rpc_restart_call(), the task can end up looping due to the RPC_TASK_SIGNALLED flag being set without the tk_rpc_status being set. Removing the redundant mechanism for signalling the task fixes the looping behaviour. Reported-by: Li Lingfeng Fixes: 39494194f93b ("SUNRPC: Fix races with rpc_killall_tasks()") Signed-off-by: Trond Myklebust Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker Signed-off-by: Sasha Levin

SUNRPC: convert RPC_TASK_* constants to enum

2025-03-07T15:45:36+00:00

[ Upstream commit 0b108e83795c9c23101f584ef7e3ab4f1f120ef0 ] The RPC_TASK_* constants are defined as macros, which means that most kernel builds will not contain their definitions in the debuginfo. However, it's quite useful for debuggers to be able to view the task state constant and interpret it correctly. Conversion to an enum will ensure the constants are present in debuginfo and can be interpreted by debuggers without needing to hard-code them and track their changes. Signed-off-by: Stephen Brennan Signed-off-by: Anna Schumaker Stable-dep-of: 5bbd6e863b15 ("SUNRPC: Prevent looping due to rpc_signal_task() races") Signed-off-by: Sasha Levin

SUNRPC: increase size of rpc_wait_queue.qlen from unsigned short to unsigned int

2024-04-13T11:07:36+00:00

[ Upstream commit 2c35f43b5a4b9cdfaa6fdd946f5a212615dac8eb ] When the NFS client is under extreme load the rpc_wait_queue.qlen counter can be overflowed. Here is an instant of the backlog queue overflow in a real world environment shown by drgn helper: rpc_task_stats(rpc_clnt): ------------------------- rpc_clnt: 0xffff92b65d2bae00 rpc_xprt: 0xffff9275db64f000 Queue: sending[64887] pending[524] backlog[30441] binding[0] XMIT task: 0xffff925c6b1d8e98 WRITE: 750654 __dta_call_status_580: 65463 __dta_call_transmit_status_579: 1 call_reserveresult: 685189 nfs_client_init_is_complete: 1 COMMIT: 584 call_reserveresult: 573 __dta_call_status_580: 11 ACCESS: 1 __dta_call_status_580: 1 GETATTR: 10 __dta_call_status_580: 4 call_reserveresult: 6 751249 tasks for server 111.222.333.444 Total tasks: 751249 count_rpc_wait_queues(xprt): ---------------------------- **** rpc_xprt: 0xffff9275db64f000 num_reqs: 65511 wait_queue: xprt_binding[0] cnt: 0 wait_queue: xprt_binding[1] cnt: 0 wait_queue: xprt_binding[2] cnt: 0 wait_queue: xprt_binding[3] cnt: 0 rpc_wait_queue[xprt_binding].qlen: 0 maxpriority: 0 wait_queue: xprt_sending[0] cnt: 0 wait_queue: xprt_sending[1] cnt: 64887 wait_queue: xprt_sending[2] cnt: 0 wait_queue: xprt_sending[3] cnt: 0 rpc_wait_queue[xprt_sending].qlen: 64887 maxpriority: 3 wait_queue: xprt_pending[0] cnt: 524 wait_queue: xprt_pending[1] cnt: 0 wait_queue: xprt_pending[2] cnt: 0 wait_queue: xprt_pending[3] cnt: 0 rpc_wait_queue[xprt_pending].qlen: 524 maxpriority: 0 wait_queue: xprt_backlog[0] cnt: 0 wait_queue: xprt_backlog[1] cnt: 685801 wait_queue: xprt_backlog[2] cnt: 0 wait_queue: xprt_backlog[3] cnt: 0 rpc_wait_queue[xprt_backlog].qlen: 30441 maxpriority: 3 [task cnt mismatch] There is no effect on operations when this overflow occurs. However it causes confusion when trying to diagnose the performance problem. Signed-off-by: Dai Ngo Reviewed-by: Jeff Layton Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin

SUNRPC: remove the maximum number of retries in call_bind_status

2023-04-19T21:06:02+00:00

Currently call_bind_status places a hard limit of 3 to the number of retries on EACCES error. This limit was done to prevent NLM unlock requests from being hang forever when the server keeps returning garbage. However this change causes problem for cases when NLM service takes longer than 9 seconds to register with the port mapper after a restart. This patch removes this hard coded limit and let the RPC handles the retry based on the standard hard/soft task semantics. Fixes: 0b760113a3a1 ("NLM: Don't hang forever on NLM unlock requests") Reported-by: Helen Chao Tested-by: Helen Chao Signed-off-by: Dai Ngo Reviewed-by: Jeff Layton Signed-off-by: Anna Schumaker

Merge tag 'nfs-for-6.1-1' of git://git.linux-nfs.org/projects/anna/linux-nfs

2022-10-13T16:58:42+00:00

Pull NFS client updates from Anna Schumaker: "New Features: - Add NFSv4.2 xattr tracepoints - Replace xprtiod WQ in rpcrdma - Flexfiles cancels I/O on layout recall or revoke Bugfixes and Cleanups: - Directly use ida_alloc() / ida_free() - Don't open-code max_t() - Prefer using strscpy over strlcpy - Remove unused forward declarations - Always return layout states on flexfiles layout return - Have LISTXATTR treat NFS4ERR_NOXATTR as an empty reply instead of error - Allow more xprtrdma memory allocations to fail without triggering a reclaim - Various other xprtrdma clean ups - Fix rpc_killall_tasks() races" * tag 'nfs-for-6.1-1' of git://git.linux-nfs.org/projects/anna/linux-nfs: (27 commits) NFSv4/flexfiles: Cancel I/O if the layout is recalled or revoked SUNRPC: Add API to force the client to disconnect SUNRPC: Add a helper to allow pNFS drivers to selectively cancel RPC calls SUNRPC: Fix races with rpc_killall_tasks() xprtrdma: Fix uninitialized variable xprtrdma: Prevent memory allocations from driving a reclaim xprtrdma: Memory allocation should be allowed to fail during connect xprtrdma: MR-related memory allocation should be allowed to fail xprtrdma: Clean up synopsis of rpcrdma_regbuf_alloc() xprtrdma: Clean up synopsis of rpcrdma_req_create() svcrdma: Clean up RPCRDMA_DEF_GFP SUNRPC: Replace the use of the xprtiod WQ in rpcrdma NFSv4.2: Add a tracepoint for listxattr NFSv4.2: Add tracepoints for getxattr, setxattr, and removexattr NFSv4.2: Move TRACE_DEFINE_ENUM(NFS4_CONTENT_*) under CONFIG_NFS_V4_2 NFSv4.2: Add special handling for LISTXATTR receiving NFS4ERR_NOXATTR nfs: remove nfs_wait_atomic_killable() and nfs_write_prepare() declaration NFSv4: remove nfs4_renewd_prepare_shutdown() declaration fs/nfs/pnfs_nfs.c: fix spelling typo and syntax error in comment NFSv4/pNFS: Always return layout stats on layout return for flexfiles ...

SUNRPC: Add a helper to allow pNFS drivers to selectively cancel RPC calls

2022-10-06T13:52:09+00:00

Add the helper rpc_cancel_tasks(), which uses a caller-defined selection function to define a set of in-flight RPC calls to cancel. This is mainly intended for pNFS drivers which are subject to a layout recall, and which may therefore want to cancel all pending I/O using that layout in order to redrive it after the layout recall has been satisfied. Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker

SUNRPC: Fix races with rpc_killall_tasks()

2022-10-06T13:52:09+00:00

Ensure that we immediately call rpc_exit_task() after waking up, and that the tk_rpc_status cannot get clobbered by some other function. Signed-off-by: Trond Myklebust Signed-off-by: Anna Schumaker

freezer,sched: Rewrite core freezer logic

2022-09-07T19:53:50+00:00

Rewrite the core freezer to behave better wrt thawing and be simpler in general. By replacing PF_FROZEN with TASK_FROZEN, a special block state, it is ensured frozen tasks stay frozen until thawed and don't randomly wake up early, as is currently possible. As such, it does away with PF_FROZEN and PF_FREEZER_SKIP, freeing up two PF_flags (yay!). Specifically; the current scheme works a little like: freezer_do_not_count(); schedule(); freezer_count(); And either the task is blocked, or it lands in try_to_freezer() through freezer_count(). Now, when it is blocked, the freezer considers it frozen and continues. However, on thawing, once pm_freezing is cleared, freezer_count() stops working, and any random/spurious wakeup will let a task run before its time. That is, thawing tries to thaw things in explicit order; kernel threads and workqueues before doing bringing SMP back before userspace etc.. However due to the above mentioned races it is entirely possible for userspace tasks to thaw (by accident) before SMP is back. This can be a fatal problem in asymmetric ISA architectures (eg ARMv9) where the userspace task requires a special CPU to run. As said; replace this with a special task state TASK_FROZEN and add the following state transitions: TASK_FREEZABLE -> TASK_FROZEN __TASK_STOPPED -> TASK_FROZEN __TASK_TRACED -> TASK_FROZEN The new TASK_FREEZABLE can be set on any state part of TASK_NORMAL (IOW. TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE) -- any such state is already required to deal with spurious wakeups and the freezer causes one such when thawing the task (since the original state is lost). The special __TASK_{STOPPED,TRACED} states *can* be restored since their canonical state is in ->jobctl. With this, frozen tasks need an explicit TASK_FROZEN wakeup and are free of undue (early / spurious) wakeups. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ingo Molnar Acked-by: Rafael J. Wysocki Link: https://lore.kernel.org/r/20220822114649.055452969@infradead.org

SUNRPC: Shrink size of struct rpc_task

2022-07-23T18:47:28+00:00

Move the field 'tk_rpc_status' so that we eliminate a 4 byte hole in the structure. For x86_64, this shrinks the size of the struct by 8 bytes. 'pahole' output before the change: /* size: 232, cachelines: 4, members: 27 */ /* sum members: 222, holes: 1, sum holes: 4 */ /* sum bitfield members: 8 bits (1 bytes) */ /* padding: 5 */ /* last cacheline: 40 bytes */ 'pahole' output after the change: /* size: 224, cachelines: 4, members: 27 */ /* padding: 1 */ /* last cacheline: 32 bytes */ Signed-off-by: Trond Myklebust

NFS: Fix memory allocation in rpc_malloc()

2022-03-22T19:52:55+00:00

When in a low memory situation, we do want rpciod to kick off direct reclaim in the case where that helps, however we don't want it looping forever in mempool_alloc(). So first try allocating from the slab using GFP_KERNEL | __GFP_NORETRY, and then fall back to a GFP_NOWAIT allocation from the mempool. Ditto for rpc_alloc_task() Signed-off-by: Trond Myklebust