From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug alb_break_llc() decides whether to break LLC preference during active load balance. It does so by testing that every runnable fair task on the source rq prefers its LLC: env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable But the two counters cover different sets. nr_pref_llc_running is updated in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued, so it follows queued tasks. h_nr_runnable is updated in set_delayed()/ clear_delayed() and drops delay-dequeued tasks. So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks, alb_break_llc() returns false, and active balance is free to pull a task off its preferred LLC. Active balance only moves runnable tasks, and this is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB skips the per-task test in can_migrate_task(). The runnable set is the one we want. Fix it on the counter side. A task should be counted in nr_pref_llc_running exactly while it is both queued on its preferred LLC (pref_llc_queued) and runnable (!sched_delayed). Define that membership once in task_pref_llc_runnable(), and adjust the counter only through pref_llc_running_inc()/pref_llc_running_dec() from the four sites that change either input: account_llc_enqueue(), account_llc_dequeue(), set_delayed() and clear_delayed(). Gating every update on the same predicate keeps the delay, wake and dequeue paths from double-counting or underflowing; see the comments at those sites for the ordering. nr_llc_running and sd->llc_counts are not touched and stay on queued semantics. Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC") Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/ Reported-by: Zhan Xusheng Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- io_uring/xattr.c | 197 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 197 insertions(+) create mode 100644 io_uring/xattr.c (limited to 'io_uring/xattr.c') diff --git a/io_uring/xattr.c b/io_uring/xattr.c new file mode 100644 index 000000000..5303df3f2 --- /dev/null +++ b/io_uring/xattr.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "../fs/internal.h" + +#include "io_uring.h" +#include "xattr.h" + +struct io_xattr { + struct file *file; + struct kernel_xattr_ctx ctx; + struct delayed_filename filename; +}; + +void io_xattr_cleanup(struct io_kiocb *req) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + + dismiss_delayed_filename(&ix->filename); + kfree(ix->ctx.kname); + kvfree(ix->ctx.kvalue); +} + +static void io_xattr_finish(struct io_kiocb *req, int ret) +{ + req->flags &= ~REQ_F_NEED_CLEANUP; + + io_xattr_cleanup(req); + io_req_set_res(req, ret, 0); +} + +static int __io_getxattr_prep(struct io_kiocb *req, + const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *name; + int ret; + + INIT_DELAYED_FILENAME(&ix->filename); + ix->ctx.kvalue = NULL; + name = u64_to_user_ptr(READ_ONCE(sqe->addr)); + ix->ctx.value = u64_to_user_ptr(READ_ONCE(sqe->addr2)); + ix->ctx.size = READ_ONCE(sqe->len); + ix->ctx.flags = READ_ONCE(sqe->xattr_flags); + + if (ix->ctx.flags) + return -EINVAL; + + ix->ctx.kname = kmalloc_obj(*ix->ctx.kname); + if (!ix->ctx.kname) + return -ENOMEM; + + ret = import_xattr_name(ix->ctx.kname, name); + if (ret) { + kfree(ix->ctx.kname); + return ret; + } + + req->flags |= REQ_F_NEED_CLEANUP; + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_fgetxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + return __io_getxattr_prep(req, sqe); +} + +int io_getxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *path; + int ret; + + if (unlikely(req->flags & REQ_F_FIXED_FILE)) + return -EBADF; + + ret = __io_getxattr_prep(req, sqe); + if (ret) + return ret; + + path = u64_to_user_ptr(READ_ONCE(sqe->addr3)); + + return delayed_getname(&ix->filename, path); +} + +int io_fgetxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = file_getxattr(req->file, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} + +int io_getxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + CLASS(filename_complete_delayed, name)(&ix->filename); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = filename_getxattr(AT_FDCWD, name, LOOKUP_FOLLOW, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} + +static int __io_setxattr_prep(struct io_kiocb *req, + const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *name; + int ret; + + INIT_DELAYED_FILENAME(&ix->filename); + name = u64_to_user_ptr(READ_ONCE(sqe->addr)); + ix->ctx.cvalue = u64_to_user_ptr(READ_ONCE(sqe->addr2)); + ix->ctx.kvalue = NULL; + ix->ctx.size = READ_ONCE(sqe->len); + ix->ctx.flags = READ_ONCE(sqe->xattr_flags); + + ix->ctx.kname = kmalloc_obj(*ix->ctx.kname); + if (!ix->ctx.kname) + return -ENOMEM; + + ret = setxattr_copy(name, &ix->ctx); + if (ret) { + kfree(ix->ctx.kname); + return ret; + } + + req->flags |= REQ_F_NEED_CLEANUP; + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_setxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *path; + int ret; + + if (unlikely(req->flags & REQ_F_FIXED_FILE)) + return -EBADF; + + ret = __io_setxattr_prep(req, sqe); + if (ret) + return ret; + + path = u64_to_user_ptr(READ_ONCE(sqe->addr3)); + + return delayed_getname(&ix->filename, path); +} + +int io_fsetxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + return __io_setxattr_prep(req, sqe); +} + +int io_fsetxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = file_setxattr(req->file, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} + +int io_setxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + CLASS(filename_complete_delayed, name)(&ix->filename); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = filename_setxattr(AT_FDCWD, name, LOOKUP_FOLLOW, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} -- cgit v1.3.1