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X-CSE-ConnectionGUID: lb9xC/pBQq2ptQb8aOKG/Q== X-CSE-MsgGUID: D8+ss5PlS0S89J5tGomF0A== X-IronPort-AV: E=McAfee;i="6800,10657,11892"; a="88519586" X-IronPort-AV: E=Sophos;i="6.25,255,1779174000"; d="scan'208";a="88519586" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2026 18:43:01 -0700 X-CSE-ConnectionGUID: wUvbxqnkQwyeT8xTBiDrwQ== X-CSE-MsgGUID: UPdEJpoEToqzE47lqLdClg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,255,1779174000"; d="scan'208";a="268998276" Received: from junjie-desk-dev.bj.intel.com ([10.238.152.71]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Aug 2026 18:42:51 -0700 From: Junjie Cao To: syzbot+8785aaf121cfb2141e0d@syzkaller.appspotmail.com Cc: liam.howlett@oracle.com, akpm@linux-foundation.org, bigeasy@linutronix.de, david@kernel.org, harry.yoo@oracle.com, jannh@google.com, jpoimboe@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, lorenzo.stoakes@oracle.com, peterz@infradead.org, pfalcato@suse.de, riel@surriel.com, syzkaller-bugs@googlegroups.com, vbabka@suse.cz, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, jhs@mojatatu.com, jiri@resnulli.us, vinicius.gomes@intel.com Subject: Re: [syzbot] [mm?] INFO: rcu detected stall in sys_munmap (2) Date: Tue, 1 Sep 2026 09:42:42 +0800 Message-ID: <20260901014242.417011-1-junjie.cao@intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <6945a977.a70a0220.207337.011c.GAE@google.com> References: <6945a977.a70a0220.207337.011c.GAE@google.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A370640005 X-Stat-Signature: 95h5h73h8s6zmrko89qwasgyismmwzyn X-Rspam-User: X-HE-Tag: 1788226982-506457 X-HE-Meta: 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 rXj0Vlbi bm2gKxRjP7LsTNZtwuSQSD6X21WlFubPUOA/MeBL9giJ0Rq8LBZ3baFAv6OOJK8RMs3Qrj3pr/GiRcMWc0nTnaVY2ByxLZssguQcnmoUCKGZ6mvfyiCAm5E+1dBMCEb5hq29lAnQJHcQAA5N0P9Kpgi7k8vhtUsF2MNfm8DMP7f/vC3Y1HxPngW1KWszm1xdcp/JzfGy4MY54G193vhCGWcZix7Z2KlCTeCdr0Bz70XctdTnQlNEVosU9FqdHa5yMl+uWLBQKVtX+nIGR/rdD1cXkgpUL4NLM7Zd8Ms6pujknzovQKxH0PYVG3U7ugVXziCXgwwNIbeHHRwJOU3MDHxOIFG5oIVzDqNvMGxBxAqSrsySo7xm0FxW1AMaWhhLYXbx9hSWPPnHIAC2yK7uxAD0scw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git abdf623ddb75b24659018d3952d8f61937306ae5 diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c index 39ac5b97aa3a..901dfd2484e1 100644 --- a/net/sched/sch_taprio.c +++ b/net/sched/sch_taprio.c @@ -83,6 +83,10 @@ struct sched_gate_list { s64 cycle_time; s64 cycle_time_extension; s64 base_time; + /* min(cycle_time, sum of intervals): the software schedule restarts + * the list after the last entry even when cycle_time is not up yet. + */ + s64 period; }; struct taprio_sched { @@ -871,12 +875,13 @@ static struct sk_buff *taprio_dequeue(struct Qdisc *sch) } static bool should_restart_cycle(const struct sched_gate_list *oper, - const struct sched_entry *entry) + const struct sched_entry *entry, + ktime_t end_time) { if (list_is_last(&entry->list, &oper->entries)) return true; - if (ktime_compare(entry->end_time, oper->cycle_end_time) == 0) + if (ktime_compare(end_time, oper->cycle_end_time) == 0) return true; return false; @@ -925,8 +930,9 @@ static enum hrtimer_restart advance_sched(struct hrtimer *timer) int num_tc = netdev_get_num_tc(dev); struct sched_entry *entry, *next; struct Qdisc *sch = q->root; - ktime_t end_time; - int tc; + ktime_t end_time, next_start, now; + int budget, tc; + s64 behind; spin_lock(&q->current_entry_lock); entry = rcu_dereference_protected(q->current_entry, @@ -952,23 +958,49 @@ static enum hrtimer_restart advance_sched(struct hrtimer *timer) goto first_run; } - if (should_restart_cycle(oper, entry)) { - next = list_first_entry(&oper->entries, struct sched_entry, - list); - oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time, - oper->cycle_time); - } else { - next = list_next_entry(entry, list); + now = hrtimer_cb_get_time(timer); + end_time = entry->end_time; + behind = ktime_sub(now, end_time); + + /* Behind, e.g. delayed timer or stepped clock: skip whole periods + * arithmetically and walk at most one more to the entry covering + * now, instead of replaying the backlog one expiry at a time. The + * cap bounds the walk; a leftover is picked up by the next expiry. + */ + if (unlikely(behind >= oper->period)) { + s64 jump = div64_s64(behind, oper->period) * oper->period; + + end_time = ktime_add_ns(end_time, jump); + oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time, jump); } - end_time = ktime_add_ns(entry->end_time, next->interval); - end_time = min_t(ktime_t, end_time, oper->cycle_end_time); + budget = 2 * oper->num_entries; + do { + if (should_restart_cycle(oper, entry, end_time)) { + next = list_first_entry(&oper->entries, + struct sched_entry, list); + oper->cycle_end_time = ktime_add_ns(oper->cycle_end_time, + oper->period); + } else { + next = list_next_entry(entry, list); + } + + next_start = end_time; + end_time = ktime_add_ns(next_start, next->interval); + end_time = min_t(ktime_t, end_time, oper->cycle_end_time); + entry = next; + } while (unlikely(ktime_compare(end_time, now) <= 0) && budget--); + /* next can be the entry already published as q->current_entry (a + * single-entry schedule, or a catch-up of whole periods), so the + * close times and budgets below are rewritten in place while + * taprio_dequeue_from_txq() may be reading them. + */ for (tc = 0; tc < num_tc; tc++) { if (next->gate_duration[tc] == oper->cycle_time) next->gate_close_time[tc] = KTIME_MAX; else - next->gate_close_time[tc] = ktime_add_ns(entry->end_time, + next->gate_close_time[tc] = ktime_add_ns(next_start, next->gate_duration[tc]); } @@ -1130,6 +1162,8 @@ static int parse_taprio_schedule(struct taprio_sched *q, struct nlattr **tb, struct sched_gate_list *new, struct netlink_ext_ack *extack) { + struct sched_entry *entry; + ktime_t cycle = 0; int err = 0; if (tb[TCA_TAPRIO_ATTR_SCHED_SINGLE_ENTRY]) { @@ -1152,13 +1186,10 @@ static int parse_taprio_schedule(struct taprio_sched *q, struct nlattr **tb, if (err < 0) return err; - if (!new->cycle_time) { - struct sched_entry *entry; - ktime_t cycle = 0; - - list_for_each_entry(entry, &new->entries, list) - cycle = ktime_add_ns(cycle, entry->interval); + list_for_each_entry(entry, &new->entries, list) + cycle = ktime_add_ns(cycle, entry->interval); + if (!new->cycle_time) { if (cycle < 0 || cycle > INT_MAX) { NL_SET_ERR_MSG(extack, "'cycle_time' is too big"); return -EINVAL; @@ -1172,6 +1203,7 @@ static int parse_taprio_schedule(struct taprio_sched *q, struct nlattr **tb, return -EINVAL; } + new->period = min(new->cycle_time, cycle); taprio_calculate_gate_durations(q, new); return 0;