6.14-stable review patch. If anyone has any objections, please let me know.
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From: Tang Yizhou yizhou.tang@shopee.com
[ Upstream commit f1ab2831e2a4312046bca79256b2efc41d373eaf ]
Patch series "Fix calculations in trace_balance_dirty_pages() for cgwb", v2.
In my experiment, I found that the output of trace_balance_dirty_pages() in the cgroup writeback scenario was strange because trace_balance_dirty_pages() always uses global_wb_domain.dirty_limit for related calculations instead of the dirty_limit of the corresponding memcg's wb_domain.
The basic idea of the fix is to store the hard dirty limit value computed in wb_position_ratio() into struct dirty_throttle_control and use it for calculations in trace_balance_dirty_pages().
This patch (of 3):
Currently, trace_balance_dirty_pages() already has 12 parameters. In the patch #3, I initially attempted to introduce an additional parameter. However, in include/linux/trace_events.h, bpf_trace_run12() only supports up to 12 parameters and bpf_trace_run13() does not exist.
To reduce the number of parameters in trace_balance_dirty_pages(), we can make it accept a pointer to struct dirty_throttle_control as a parameter. To achieve this, we need to move the definition of struct dirty_throttle_control from mm/page-writeback.c to include/linux/writeback.h.
Link: https://lkml.kernel.org/r/20250304110318.159567-1-yizhou.tang@shopee.com Link: https://lkml.kernel.org/r/20250304110318.159567-2-yizhou.tang@shopee.com Signed-off-by: Tang Yizhou yizhou.tang@shopee.com Cc: Alexei Starovoitov ast@kernel.org Cc: Christian Brauner brauner@kernel.org Cc: Steven Rostedt rostedt@goodmis.org Cc: Jan Kara jack@suse.cz Cc: "Masami Hiramatsu (Google)" mhiramat@kernel.org Cc: Matthew Wilcow (Oracle) willy@infradead.org Cc: Tang Yizhou yizhou.tang@shopee.com Cc: Tejun Heo tj@kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Stable-dep-of: 6cc4c3aa714b ("writeback: fix calculations in trace_balance_dirty_pages() for cgwb") Signed-off-by: Sasha Levin sashal@kernel.org --- include/linux/writeback.h | 23 +++++++++++++++++++++ include/trace/events/writeback.h | 16 ++++++--------- mm/page-writeback.c | 35 ++------------------------------ 3 files changed, 31 insertions(+), 43 deletions(-)
diff --git a/include/linux/writeback.h b/include/linux/writeback.h index d11b903c2edb8..32095928365ce 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -313,6 +313,29 @@ static inline void cgroup_writeback_umount(struct super_block *sb) /* * mm/page-writeback.c */ +/* consolidated parameters for balance_dirty_pages() and its subroutines */ +struct dirty_throttle_control { +#ifdef CONFIG_CGROUP_WRITEBACK + struct wb_domain *dom; + struct dirty_throttle_control *gdtc; /* only set in memcg dtc's */ +#endif + struct bdi_writeback *wb; + struct fprop_local_percpu *wb_completions; + + unsigned long avail; /* dirtyable */ + unsigned long dirty; /* file_dirty + write + nfs */ + unsigned long thresh; /* dirty threshold */ + unsigned long bg_thresh; /* dirty background threshold */ + + unsigned long wb_dirty; /* per-wb counterparts */ + unsigned long wb_thresh; + unsigned long wb_bg_thresh; + + unsigned long pos_ratio; + bool freerun; + bool dirty_exceeded; +}; + void laptop_io_completion(struct backing_dev_info *info); void laptop_sync_completion(void); void laptop_mode_timer_fn(struct timer_list *t); diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index a261e86e61fac..3213b90237944 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -629,11 +629,7 @@ TRACE_EVENT(bdi_dirty_ratelimit, TRACE_EVENT(balance_dirty_pages,
TP_PROTO(struct bdi_writeback *wb, - unsigned long thresh, - unsigned long bg_thresh, - unsigned long dirty, - unsigned long bdi_thresh, - unsigned long bdi_dirty, + struct dirty_throttle_control *dtc, unsigned long dirty_ratelimit, unsigned long task_ratelimit, unsigned long dirtied, @@ -641,7 +637,7 @@ TRACE_EVENT(balance_dirty_pages, long pause, unsigned long start_time),
- TP_ARGS(wb, thresh, bg_thresh, dirty, bdi_thresh, bdi_dirty, + TP_ARGS(wb, dtc, dirty_ratelimit, task_ratelimit, dirtied, period, pause, start_time),
@@ -664,16 +660,16 @@ TRACE_EVENT(balance_dirty_pages, ),
TP_fast_assign( - unsigned long freerun = (thresh + bg_thresh) / 2; + unsigned long freerun = (dtc->thresh + dtc->bg_thresh) / 2; strscpy_pad(__entry->bdi, bdi_dev_name(wb->bdi), 32);
__entry->limit = global_wb_domain.dirty_limit; __entry->setpoint = (global_wb_domain.dirty_limit + freerun) / 2; - __entry->dirty = dirty; + __entry->dirty = dtc->dirty; __entry->bdi_setpoint = __entry->setpoint * - bdi_thresh / (thresh + 1); - __entry->bdi_dirty = bdi_dirty; + dtc->wb_thresh / (dtc->thresh + 1); + __entry->bdi_dirty = dtc->wb_dirty; __entry->dirty_ratelimit = KBps(dirty_ratelimit); __entry->task_ratelimit = KBps(task_ratelimit); __entry->dirtied = dirtied; diff --git a/mm/page-writeback.c b/mm/page-writeback.c index eb55ece39c565..e980b2aec3529 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -120,29 +120,6 @@ EXPORT_SYMBOL(laptop_mode);
struct wb_domain global_wb_domain;
-/* consolidated parameters for balance_dirty_pages() and its subroutines */ -struct dirty_throttle_control { -#ifdef CONFIG_CGROUP_WRITEBACK - struct wb_domain *dom; - struct dirty_throttle_control *gdtc; /* only set in memcg dtc's */ -#endif - struct bdi_writeback *wb; - struct fprop_local_percpu *wb_completions; - - unsigned long avail; /* dirtyable */ - unsigned long dirty; /* file_dirty + write + nfs */ - unsigned long thresh; /* dirty threshold */ - unsigned long bg_thresh; /* dirty background threshold */ - - unsigned long wb_dirty; /* per-wb counterparts */ - unsigned long wb_thresh; - unsigned long wb_bg_thresh; - - unsigned long pos_ratio; - bool freerun; - bool dirty_exceeded; -}; - /* * Length of period for aging writeout fractions of bdis. This is an * arbitrarily chosen number. The longer the period, the slower fractions will @@ -1962,11 +1939,7 @@ static int balance_dirty_pages(struct bdi_writeback *wb, */ if (pause < min_pause) { trace_balance_dirty_pages(wb, - sdtc->thresh, - sdtc->bg_thresh, - sdtc->dirty, - sdtc->wb_thresh, - sdtc->wb_dirty, + sdtc, dirty_ratelimit, task_ratelimit, pages_dirtied, @@ -1991,11 +1964,7 @@ static int balance_dirty_pages(struct bdi_writeback *wb,
pause: trace_balance_dirty_pages(wb, - sdtc->thresh, - sdtc->bg_thresh, - sdtc->dirty, - sdtc->wb_thresh, - sdtc->wb_dirty, + sdtc, dirty_ratelimit, task_ratelimit, pages_dirtied,