From 3d1c7fd97e4c5e54034231cd11319079dfaed60e Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Thu, 6 May 2021 18:05:00 -0700 Subject: [PATCH] delayacct: clear right task's flag after blkio completes When I was implementing a latency analyzer tool by using task->delays and other things, I found an issue in delayacct. The issue is it should clear the target's flag instead of current's in delayacct_blkio_end(). When I git blame delayacct, I found there're some similar issues we have fixed in delayacct_blkio_end(). - Commit c96f5471ce7d ("delayacct: Account blkio completion on the correct task") fixed the issue that it should account blkio completion on the target task instead of current. - Commit b512719f771a ("delayacct: fix crash in delayacct_blkio_end() after delayacct init failure") fixed the issue that it should check target task's delays instead of current task'. It seems that delayacct_blkio_{begin, end} are error prone. So I introduce a new paratmeter - the target task 'p' - to these helpers. After that change, the callsite will specifilly set the right task, which should make it less error prone. Link: https://lkml.kernel.org/r/20210414083720.24083-1-laoar.shao@gmail.com Signed-off-by: Yafang Shao Cc: Tejun Heo Cc: Josh Snyder Cc: Jens Axboe Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/delayacct.h | 20 ++++++++++---------- mm/memory.c | 8 ++++---- 2 files changed, 14 insertions(+), 14 deletions(-) diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h index 2d3bdcc..21651f9 100644 --- a/include/linux/delayacct.h +++ b/include/linux/delayacct.h @@ -82,16 +82,16 @@ static inline int delayacct_is_task_waiting_on_io(struct task_struct *p) return 0; } -static inline void delayacct_set_flag(int flag) +static inline void delayacct_set_flag(struct task_struct *p, int flag) { - if (current->delays) - current->delays->flags |= flag; + if (p->delays) + p->delays->flags |= flag; } -static inline void delayacct_clear_flag(int flag) +static inline void delayacct_clear_flag(struct task_struct *p, int flag) { - if (current->delays) - current->delays->flags &= ~flag; + if (p->delays) + p->delays->flags &= ~flag; } static inline void delayacct_tsk_init(struct task_struct *tsk) @@ -114,7 +114,7 @@ static inline void delayacct_tsk_free(struct task_struct *tsk) static inline void delayacct_blkio_start(void) { - delayacct_set_flag(DELAYACCT_PF_BLKIO); + delayacct_set_flag(current, DELAYACCT_PF_BLKIO); if (current->delays) __delayacct_blkio_start(); } @@ -123,7 +123,7 @@ static inline void delayacct_blkio_end(struct task_struct *p) { if (p->delays) __delayacct_blkio_end(p); - delayacct_clear_flag(DELAYACCT_PF_BLKIO); + delayacct_clear_flag(p, DELAYACCT_PF_BLKIO); } static inline int delayacct_add_tsk(struct taskstats *d, @@ -166,9 +166,9 @@ static inline void delayacct_thrashing_end(void) } #else -static inline void delayacct_set_flag(int flag) +static inline void delayacct_set_flag(struct task_struct *p, int flag) {} -static inline void delayacct_clear_flag(int flag) +static inline void delayacct_clear_flag(struct task_struct *p, int flag) {} static inline void delayacct_init(void) {} diff --git a/mm/memory.c b/mm/memory.c index cbdc2cd..8c491f8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3339,7 +3339,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) } - delayacct_set_flag(DELAYACCT_PF_SWAPIN); + delayacct_set_flag(current, DELAYACCT_PF_SWAPIN); page = lookup_swap_cache(entry, vma, vmf->address); swapcache = page; @@ -3388,7 +3388,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) vmf->address, &vmf->ptl); if (likely(pte_same(*vmf->pte, vmf->orig_pte))) ret = VM_FAULT_OOM; - delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN); goto unlock; } @@ -3402,13 +3402,13 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) * owner processes (which may be unknown at hwpoison time) */ ret = VM_FAULT_HWPOISON; - delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN); goto out_release; } locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags); - delayacct_clear_flag(DELAYACCT_PF_SWAPIN); + delayacct_clear_flag(current, DELAYACCT_PF_SWAPIN); if (!locked) { ret |= VM_FAULT_RETRY; goto out_release; -- 2.7.4