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 --- rust/syn/macros.rs | 184 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 184 insertions(+) create mode 100644 rust/syn/macros.rs (limited to 'rust/syn/macros.rs') diff --git a/rust/syn/macros.rs b/rust/syn/macros.rs new file mode 100644 index 000000000..8676f6492 --- /dev/null +++ b/rust/syn/macros.rs @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +#[cfg_attr( + not(any(feature = "full", feature = "derive")), + allow(unknown_lints, unused_macro_rules) +)] +macro_rules! ast_struct { + ( + $(#[$attr:meta])* + $pub:ident $struct:ident $name:ident #full $body:tt + ) => { + check_keyword_matches!(pub $pub); + check_keyword_matches!(struct $struct); + + #[cfg(feature = "full")] + $(#[$attr])* $pub $struct $name $body + + #[cfg(not(feature = "full"))] + $(#[$attr])* $pub $struct $name { + _noconstruct: ::std::marker::PhantomData<::proc_macro2::Span>, + } + + #[cfg(all(not(feature = "full"), feature = "printing"))] + impl ::quote::ToTokens for $name { + fn to_tokens(&self, _: &mut ::proc_macro2::TokenStream) { + unreachable!() + } + } + }; + + ( + $(#[$attr:meta])* + $pub:ident $struct:ident $name:ident $body:tt + ) => { + check_keyword_matches!(pub $pub); + check_keyword_matches!(struct $struct); + + $(#[$attr])* $pub $struct $name $body + }; +} + +#[cfg(any(feature = "full", feature = "derive"))] +macro_rules! ast_enum { + ( + $(#[$enum_attr:meta])* + $pub:ident $enum:ident $name:ident $body:tt + ) => { + check_keyword_matches!(pub $pub); + check_keyword_matches!(enum $enum); + + $(#[$enum_attr])* $pub $enum $name $body + }; +} + +macro_rules! ast_enum_of_structs { + ( + $(#[$enum_attr:meta])* + $pub:ident $enum:ident $name:ident $body:tt + ) => { + check_keyword_matches!(pub $pub); + check_keyword_matches!(enum $enum); + + $(#[$enum_attr])* $pub $enum $name $body + + ast_enum_of_structs_impl!($name $body); + + #[cfg(feature = "printing")] + generate_to_tokens!(() tokens $name $body); + }; +} + +macro_rules! ast_enum_of_structs_impl { + ( + $name:ident { + $( + $(#[cfg $cfg_attr:tt])* + $(#[doc $($doc_attr:tt)*])* + $variant:ident $( ($member:ident) )*, + )* + } + ) => { + $($( + ast_enum_from_struct!($name::$variant, $member); + )*)* + }; +} + +macro_rules! ast_enum_from_struct { + // No From for verbatim variants. + ($name:ident::Verbatim, $member:ident) => {}; + + ($name:ident::$variant:ident, $member:ident) => { + impl From<$member> for $name { + fn from(e: $member) -> $name { + $name::$variant(e) + } + } + }; +} + +#[cfg(feature = "printing")] +macro_rules! generate_to_tokens { + ( + ($($arms:tt)*) $tokens:ident $name:ident { + $(#[cfg $cfg_attr:tt])* + $(#[doc $($doc_attr:tt)*])* + $variant:ident, + $($next:tt)* + } + ) => { + generate_to_tokens!( + ($($arms)* $(#[cfg $cfg_attr])* $name::$variant => {}) + $tokens $name { $($next)* } + ); + }; + + ( + ($($arms:tt)*) $tokens:ident $name:ident { + $(#[cfg $cfg_attr:tt])* + $(#[doc $($doc_attr:tt)*])* + $variant:ident($member:ident), + $($next:tt)* + } + ) => { + generate_to_tokens!( + ($($arms)* $(#[cfg $cfg_attr])* $name::$variant(_e) => _e.to_tokens($tokens),) + $tokens $name { $($next)* } + ); + }; + + (($($arms:tt)*) $tokens:ident $name:ident {}) => { + #[cfg_attr(docsrs, doc(cfg(feature = "printing")))] + impl ::quote::ToTokens for $name { + fn to_tokens(&self, $tokens: &mut ::proc_macro2::TokenStream) { + match self { + $($arms)* + } + } + } + }; +} + +// Rustdoc bug: does not respect the doc(hidden) on some items. +#[cfg(all(doc, feature = "parsing"))] +macro_rules! pub_if_not_doc { + ($(#[$m:meta])* $pub:ident $($item:tt)*) => { + check_keyword_matches!(pub $pub); + + $(#[$m])* + $pub(crate) $($item)* + }; +} + +#[cfg(all(not(doc), feature = "parsing"))] +macro_rules! pub_if_not_doc { + ($(#[$m:meta])* $pub:ident $($item:tt)*) => { + check_keyword_matches!(pub $pub); + + $(#[$m])* + $pub $($item)* + }; +} + +macro_rules! check_keyword_matches { + (enum enum) => {}; + (pub pub) => {}; + (struct struct) => {}; +} + +#[cfg(any(feature = "full", feature = "derive"))] +macro_rules! return_impl_trait { + ( + $(#[$attr:meta])* + $vis:vis fn $name:ident $args:tt -> $impl_trait:ty [$concrete:ty] $body:block + ) => { + #[cfg(not(docsrs))] + $(#[$attr])* + $vis fn $name $args -> $concrete $body + + #[cfg(docsrs)] + $(#[$attr])* + $vis fn $name $args -> $impl_trait $body + }; +} -- cgit v1.3.1