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X-AuditID: a67dfc5b-d6dff70000001748-fb-64e2ded67158 From: Byungchul Park To: linux-kernel@vger.kernel.org Cc: kernel_team@skhynix.com, torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com, linux-ide@vger.kernel.org, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, will@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, joel@joelfernandes.org, sashal@kernel.org, daniel.vetter@ffwll.ch, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu, willy@infradead.org, david@fromorbit.com, amir73il@gmail.com, gregkh@linuxfoundation.org, kernel-team@lge.com, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org, minchan@kernel.org, hannes@cmpxchg.org, vdavydov.dev@gmail.com, sj@kernel.org, jglisse@redhat.com, dennis@kernel.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, vbabka@suse.cz, ngupta@vflare.org, linux-block@vger.kernel.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, jlayton@kernel.org, dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org, dri-devel@lists.freedesktop.org, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com, 42.hyeyoo@gmail.com, chris.p.wilson@intel.com, gwan-gyeong.mun@intel.com, max.byungchul.park@gmail.com, boqun.feng@gmail.com, longman@redhat.com, hdanton@sina.com, her0gyugyu@gmail.com Subject: [RESEND PATCH v10 17/25] dept: Track timeout waits separately with a new Kconfig Date: Mon, 21 Aug 2023 12:46:29 +0900 Message-Id: <20230821034637.34630-18-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230821034637.34630-1-byungchul@sk.com> References: <20230821034637.34630-1-byungchul@sk.com> X-Brightmail-Tracker: H4sIAAAAAAAAAzWSbUxTZxiGfd9zzntOqzUnVeMZzI91YUswCijMR6NuGqMnzCVblonoD2ns iTQDNC2fmyYwKzoBI0RkAlOKW1cpTC1+IFhSy4AWolZhjBlo1mpUwpeytbPQ4VqNf55cue/c 16+Ho5RtTBSnzcqWdFnqDBWR0/LxefUrBzw+TfxoeTyUl8aD/5/jNNReaiTg/tWCoPFqEYaR 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H4sIAAAAAAAAAzWSfUzMcRzHfb+/p+s4fk7Tb9jYeZoQbcVnYzGb9RuVh2nmYXO/ud90emB3 RGG7dIWeVk1depLiulWUyyiKXOuSFlFS1M2dx4iIix483DH/fPba+73366+PhJAXUDMk6qhD oiZKiFDQUlIasip+aZfNoVr+5bkXZKQsB+e30yTkV1bQ0H6lHEHFtTgM/U2B8HR4AMFY20MC DFntCC7Y+wi4ZrUhqDedpKHj1WTodA7S0JKVTEN8SSUNjz6MY+jNzsRQbg6G1vRiDA0jb0kw 9NOQZ4jHrvMOw4ixjAGjbj44TLkMjNt9ocXWRUFjQQsF9c8Ww7nCXhrq6ltIsNY4MHTczKfB VvGbglbrPRLaM1IpuPypmIYPw0YCjM5BBh43FGGo0rtsiV9/UdCc2oAh8eJVDJ09txDcPv0C g7mii4ZG5wCGanMWAaOlTQgcaR8ZSEgZYSAvLg1BckI2CQ9/NlOg7/WHsR/59NpVfOPAIMHr q4/w9cNFJH+/mONrc/sYXn/7GcMXmQ/z1SZvvqSuH/MXhpwUby47Q/PmoUyGT/rYiflPDx4w /L2cMZJ/1WnAm2ftlK5WiRHqaFGzLEApDbvcpycODimPWpouYR26G5SEPCQc68eNGy2Um2l2 IdfdPUK42ZOdw1WnvnHlUgnBnprImT630e5iGruDu25vx24m2fncWHne37GMXcGNNr6h/kln c+VVDX9FHq7cfOsmcrOc9ee+2F+S6UhahCaUIU91VHSkoI7w99GGh8VEqY/67D0QaUaupzGe GM+oQd86Ai2IlSDFJJlylkMlp4RobUykBXESQuEpm/ndrpLLVEJMrKg5sEdzOELUWtBMCanw km3YLirl7D7hkBguigdFzf8WSzxm6NCSY7pLjuF1a6YnhqyMtcTW3sELAhzZnL27eeN+K5wd NXkdowxb2raUzpsUZIsLv9rl8zIoIKl4NHhTjIf6eMnv3UBOSxCs3rvUyUtv+J1fn739daqu 1q7s84ndXRa0eWurb+b71QIZOqUn7EnBNliWsy00ctHbtMWnCuvsuVPn1ihIbZjg601otMIf yW5ULjADAAA= X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Waits with valid timeouts don't actually cause deadlocks. However, Dept has been reporting the cases as well because it's worth informing the circular dependency for some cases where, for example, timeout is used to avoid a deadlock but not meant to be expired. However, yes, there are also a lot of, even more, cases where timeout is used for its clear purpose and meant to be expired. Let Dept report these as an information rather than shouting DEADLOCK. Plus, introduced CONFIG_DEPT_AGGRESSIVE_TIMEOUT_WAIT Kconfig to make it optional so that any reports involving waits with timeouts can be turned on/off depending on the purpose. Signed-off-by: Byungchul Park --- include/linux/dept.h | 15 ++++++--- include/linux/dept_ldt.h | 6 ++-- include/linux/dept_sdt.h | 12 +++++--- kernel/dependency/dept.c | 66 ++++++++++++++++++++++++++++++++++------ lib/Kconfig.debug | 10 ++++++ 5 files changed, 89 insertions(+), 20 deletions(-) diff --git a/include/linux/dept.h b/include/linux/dept.h index 583e8fe2dd7b..0aa8d90558a9 100644 --- a/include/linux/dept.h +++ b/include/linux/dept.h @@ -270,6 +270,11 @@ struct dept_wait { * whether this wait is for commit in scheduler */ bool sched_sleep; + + /* + * whether a timeout is set + */ + bool timeout; }; }; }; @@ -458,6 +463,7 @@ struct dept_task { bool stage_sched_map; const char *stage_w_fn; unsigned long stage_ip; + bool stage_timeout; /* * the number of missing ecxts @@ -496,6 +502,7 @@ struct dept_task { .stage_sched_map = false, \ .stage_w_fn = NULL, \ .stage_ip = 0UL, \ + .stage_timeout = false, \ .missing_ecxt = 0, \ .hardirqs_enabled = false, \ .softirqs_enabled = false, \ @@ -513,8 +520,8 @@ extern void dept_map_init(struct dept_map *m, struct dept_key *k, int sub_u, con extern void dept_map_reinit(struct dept_map *m, struct dept_key *k, int sub_u, const char *n); extern void dept_map_copy(struct dept_map *to, struct dept_map *from); -extern void dept_wait(struct dept_map *m, unsigned long w_f, unsigned long ip, const char *w_fn, int sub_l); -extern void dept_stage_wait(struct dept_map *m, struct dept_key *k, unsigned long ip, const char *w_fn); +extern void dept_wait(struct dept_map *m, unsigned long w_f, unsigned long ip, const char *w_fn, int sub_l, long timeout); +extern void dept_stage_wait(struct dept_map *m, struct dept_key *k, unsigned long ip, const char *w_fn, long timeout); extern void dept_request_event_wait_commit(void); extern void dept_clean_stage(void); extern void dept_stage_event(struct task_struct *t, unsigned long ip); @@ -566,8 +573,8 @@ struct dept_task { }; #define dept_map_reinit(m, k, su, n) do { (void)(n); (void)(k); } while (0) #define dept_map_copy(t, f) do { } while (0) -#define dept_wait(m, w_f, ip, w_fn, sl) do { (void)(w_fn); } while (0) -#define dept_stage_wait(m, k, ip, w_fn) do { (void)(k); (void)(w_fn); } while (0) +#define dept_wait(m, w_f, ip, w_fn, sl, t) do { (void)(w_fn); } while (0) +#define dept_stage_wait(m, k, ip, w_fn, t) do { (void)(k); (void)(w_fn); } while (0) #define dept_request_event_wait_commit() do { } while (0) #define dept_clean_stage() do { } while (0) #define dept_stage_event(t, ip) do { } while (0) diff --git a/include/linux/dept_ldt.h b/include/linux/dept_ldt.h index 062613e89fc3..8adf298dfcb8 100644 --- a/include/linux/dept_ldt.h +++ b/include/linux/dept_ldt.h @@ -27,7 +27,7 @@ else if (t) \ dept_ecxt_enter(m, LDT_EVT_L, i, "trylock", "unlock", sl);\ else { \ - dept_wait(m, LDT_EVT_L, i, "lock", sl); \ + dept_wait(m, LDT_EVT_L, i, "lock", sl, false); \ dept_ecxt_enter(m, LDT_EVT_L, i, "lock", "unlock", sl);\ } \ } while (0) @@ -39,7 +39,7 @@ else if (t) \ dept_ecxt_enter(m, LDT_EVT_R, i, "read_trylock", "read_unlock", sl);\ else { \ - dept_wait(m, q ? LDT_EVT_RW : LDT_EVT_W, i, "read_lock", sl);\ + dept_wait(m, q ? LDT_EVT_RW : LDT_EVT_W, i, "read_lock", sl, false);\ dept_ecxt_enter(m, LDT_EVT_R, i, "read_lock", "read_unlock", sl);\ } \ } while (0) @@ -51,7 +51,7 @@ else if (t) \ dept_ecxt_enter(m, LDT_EVT_W, i, "write_trylock", "write_unlock", sl);\ else { \ - dept_wait(m, LDT_EVT_RW, i, "write_lock", sl); \ + dept_wait(m, LDT_EVT_RW, i, "write_lock", sl, false);\ dept_ecxt_enter(m, LDT_EVT_W, i, "write_lock", "write_unlock", sl);\ } \ } while (0) diff --git a/include/linux/dept_sdt.h b/include/linux/dept_sdt.h index 12a793b90c7e..21fce525f031 100644 --- a/include/linux/dept_sdt.h +++ b/include/linux/dept_sdt.h @@ -22,11 +22,12 @@ #define sdt_map_init_key(m, k) dept_map_init(m, k, 0, #m) -#define sdt_wait(m) \ +#define sdt_wait_timeout(m, t) \ do { \ dept_request_event(m); \ - dept_wait(m, 1UL, _THIS_IP_, __func__, 0); \ + dept_wait(m, 1UL, _THIS_IP_, __func__, 0, t); \ } while (0) +#define sdt_wait(m) sdt_wait_timeout(m, -1L) /* * sdt_might_sleep() and its family will be committed in __schedule() @@ -37,12 +38,13 @@ /* * Use the code location as the class key if an explicit map is not used. */ -#define sdt_might_sleep_start(m) \ +#define sdt_might_sleep_start_timeout(m, t) \ do { \ struct dept_map *__m = m; \ static struct dept_key __key; \ - dept_stage_wait(__m, __m ? NULL : &__key, _THIS_IP_, __func__);\ + dept_stage_wait(__m, __m ? NULL : &__key, _THIS_IP_, __func__, t);\ } while (0) +#define sdt_might_sleep_start(m) sdt_might_sleep_start_timeout(m, -1L) #define sdt_might_sleep_end() dept_clean_stage() @@ -52,7 +54,9 @@ #else /* !CONFIG_DEPT */ #define sdt_map_init(m) do { } while (0) #define sdt_map_init_key(m, k) do { (void)(k); } while (0) +#define sdt_wait_timeout(m, t) do { } while (0) #define sdt_wait(m) do { } while (0) +#define sdt_might_sleep_start_timeout(m, t) do { } while (0) #define sdt_might_sleep_start(m) do { } while (0) #define sdt_might_sleep_end() do { } while (0) #define sdt_ecxt_enter(m) do { } while (0) diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c index 8454f0a14d67..52537c099b68 100644 --- a/kernel/dependency/dept.c +++ b/kernel/dependency/dept.c @@ -740,6 +740,8 @@ static void print_diagram(struct dept_dep *d) if (!irqf) { print_spc(spc, "[S] %s(%s:%d)\n", c_fn, fc_n, fc->sub_id); print_spc(spc, "[W] %s(%s:%d)\n", w_fn, tc_n, tc->sub_id); + if (w->timeout) + print_spc(spc, "--------------- >8 timeout ---------------\n"); print_spc(spc, "[E] %s(%s:%d)\n", e_fn, fc_n, fc->sub_id); } } @@ -793,6 +795,24 @@ static void print_dep(struct dept_dep *d) static void save_current_stack(int skip); +static bool is_timeout_wait_circle(struct dept_class *c) +{ + struct dept_class *fc = c->bfs_parent; + struct dept_class *tc = c; + + do { + struct dept_dep *d = lookup_dep(fc, tc); + + if (d->wait->timeout) + return true; + + tc = fc; + fc = fc->bfs_parent; + } while (tc != c); + + return false; +} + /* * Print all classes in a circle. */ @@ -815,10 +835,14 @@ static void print_circle(struct dept_class *c) pr_warn("summary\n"); pr_warn("---------------------------------------------------\n"); - if (fc == tc) + if (is_timeout_wait_circle(c)) { + pr_warn("NOT A DEADLOCK BUT A CIRCULAR DEPENDENCY\n"); + pr_warn("CHECK IF THE TIMEOUT IS INTENDED\n\n"); + } else if (fc == tc) { pr_warn("*** AA DEADLOCK ***\n\n"); - else + } else { pr_warn("*** DEADLOCK ***\n\n"); + } i = 0; do { @@ -1564,7 +1588,8 @@ static void add_dep(struct dept_ecxt *e, struct dept_wait *w) static atomic_t wgen = ATOMIC_INIT(1); static void add_wait(struct dept_class *c, unsigned long ip, - const char *w_fn, int sub_l, bool sched_sleep) + const char *w_fn, int sub_l, bool sched_sleep, + bool timeout) { struct dept_task *dt = dept_task(); struct dept_wait *w; @@ -1584,6 +1609,7 @@ static void add_wait(struct dept_class *c, unsigned long ip, w->wait_fn = w_fn; w->wait_stack = get_current_stack(); w->sched_sleep = sched_sleep; + w->timeout = timeout; cxt = cur_cxt(); if (cxt == DEPT_CXT_HIRQ || cxt == DEPT_CXT_SIRQ) @@ -2338,7 +2364,7 @@ static struct dept_class *check_new_class(struct dept_key *local, */ static void __dept_wait(struct dept_map *m, unsigned long w_f, unsigned long ip, const char *w_fn, int sub_l, - bool sched_sleep, bool sched_map) + bool sched_sleep, bool sched_map, bool timeout) { int e; @@ -2361,7 +2387,7 @@ static void __dept_wait(struct dept_map *m, unsigned long w_f, if (!c) continue; - add_wait(c, ip, w_fn, sub_l, sched_sleep); + add_wait(c, ip, w_fn, sub_l, sched_sleep, timeout); } } @@ -2403,14 +2429,23 @@ static void __dept_event(struct dept_map *m, unsigned long e_f, } void dept_wait(struct dept_map *m, unsigned long w_f, - unsigned long ip, const char *w_fn, int sub_l) + unsigned long ip, const char *w_fn, int sub_l, + long timeoutval) { struct dept_task *dt = dept_task(); unsigned long flags; + bool timeout; if (unlikely(!dept_working())) return; + timeout = timeoutval > 0 && timeoutval < MAX_SCHEDULE_TIMEOUT; + +#if !defined(CONFIG_DEPT_AGGRESSIVE_TIMEOUT_WAIT) + if (timeout) + return; +#endif + if (dt->recursive) return; @@ -2419,21 +2454,30 @@ void dept_wait(struct dept_map *m, unsigned long w_f, flags = dept_enter(); - __dept_wait(m, w_f, ip, w_fn, sub_l, false, false); + __dept_wait(m, w_f, ip, w_fn, sub_l, false, false, timeout); dept_exit(flags); } EXPORT_SYMBOL_GPL(dept_wait); void dept_stage_wait(struct dept_map *m, struct dept_key *k, - unsigned long ip, const char *w_fn) + unsigned long ip, const char *w_fn, + long timeoutval) { struct dept_task *dt = dept_task(); unsigned long flags; + bool timeout; if (unlikely(!dept_working())) return; + timeout = timeoutval > 0 && timeoutval < MAX_SCHEDULE_TIMEOUT; + +#if !defined(CONFIG_DEPT_AGGRESSIVE_TIMEOUT_WAIT) + if (timeout) + return; +#endif + if (m && m->nocheck) return; @@ -2481,6 +2525,7 @@ void dept_stage_wait(struct dept_map *m, struct dept_key *k, dt->stage_w_fn = w_fn; dt->stage_ip = ip; + dt->stage_timeout = timeout; unlock: arch_spin_unlock(&stage_spin); @@ -2506,6 +2551,7 @@ void dept_clean_stage(void) dt->stage_sched_map = false; dt->stage_w_fn = NULL; dt->stage_ip = 0UL; + dt->stage_timeout = false; arch_spin_unlock(&stage_spin); dept_exit_recursive(flags); @@ -2523,6 +2569,7 @@ void dept_request_event_wait_commit(void) unsigned long ip; const char *w_fn; bool sched_map; + bool timeout; if (unlikely(!dept_working())) return; @@ -2545,6 +2592,7 @@ void dept_request_event_wait_commit(void) w_fn = dt->stage_w_fn; ip = dt->stage_ip; sched_map = dt->stage_sched_map; + timeout = dt->stage_timeout; /* * Avoid zero wgen. @@ -2552,7 +2600,7 @@ void dept_request_event_wait_commit(void) wg = atomic_inc_return(&wgen) ?: atomic_inc_return(&wgen); WRITE_ONCE(dt->stage_m.wgen, wg); - __dept_wait(&dt->stage_m, 1UL, ip, w_fn, 0, true, sched_map); + __dept_wait(&dt->stage_m, 1UL, ip, w_fn, 0, true, sched_map, timeout); exit: dept_exit(flags); } diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index aa62caa4dc14..f78b3d721a2b 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1234,6 +1234,16 @@ config DEPT noting, to mitigate the impact by the false positives, multi reporting has been supported. +config DEPT_AGGRESSIVE_TIMEOUT_WAIT + bool "Aggressively track even timeout waits" + depends on DEPT + default n + help + Timeout wait doesn't contribute to a deadlock. However, + informing a circular dependency might be helpful for cases + that timeout is used to avoid a deadlock. Say N if you'd like + to avoid verbose reports. + config LOCK_DEBUGGING_SUPPORT bool depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT