From 5541c93cdf0cc0bb7f6065b43509171838665ea1 Mon Sep 17 00:00:00 2001 From: Tony Luck Date: Sat, 30 Apr 2016 14:33:56 +0200 Subject: [PATCH] x86/mce: Look in genpool instead of mcelog for pending error records A couple of issues here: 1) MCE_LOG_LEN is only 32 - so we may have more pending records than will fit in the buffer on high core count CPUs. 2) During a panic we may have a lot of duplicate records because multiple logical CPUs may have seen and logged the same error because some banks are shared. Switch to using the genpool to look for the pending records. Squeeze out duplicated records. Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Ashok Raj Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-edac Link: http://lkml.kernel.org/r/1462019637-16474-7-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mcheck/mce-genpool.c | 46 +++++++++++++++++++++++ arch/x86/kernel/cpu/mcheck/mce-internal.h | 15 ++++++++ arch/x86/kernel/cpu/mcheck/mce.c | 21 +++++------ 3 files changed, 70 insertions(+), 12 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce-genpool.c b/arch/x86/kernel/cpu/mcheck/mce-genpool.c index 2658e2af74ec..93d824ec3120 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-genpool.c +++ b/arch/x86/kernel/cpu/mcheck/mce-genpool.c @@ -26,6 +26,52 @@ static struct gen_pool *mce_evt_pool; static LLIST_HEAD(mce_event_llist); static char gen_pool_buf[MCE_POOLSZ]; +/* + * Compare the record "t" with each of the records on list "l" to see if + * an equivalent one is present in the list. + */ +static bool is_duplicate_mce_record(struct mce_evt_llist *t, struct mce_evt_llist *l) +{ + struct mce_evt_llist *node; + struct mce *m1, *m2; + + m1 = &t->mce; + + llist_for_each_entry(node, &l->llnode, llnode) { + m2 = &node->mce; + + if (!mce_cmp(m1, m2)) + return true; + } + return false; +} + +/* + * The system has panicked - we'd like to peruse the list of MCE records + * that have been queued, but not seen by anyone yet. The list is in + * reverse time order, so we need to reverse it. While doing that we can + * also drop duplicate records (these were logged because some banks are + * shared between cores or by all threads on a socket). + */ +struct llist_node *mce_gen_pool_prepare_records(void) +{ + struct llist_node *head; + LLIST_HEAD(new_head); + struct mce_evt_llist *node, *t; + + head = llist_del_all(&mce_event_llist); + if (!head) + return NULL; + + /* squeeze out duplicates while reversing order */ + llist_for_each_entry_safe(node, t, head, llnode) { + if (!is_duplicate_mce_record(node, t)) + llist_add(&node->llnode, &new_head); + } + + return new_head.first; +} + void mce_gen_pool_process(void) { struct llist_node *head; diff --git a/arch/x86/kernel/cpu/mcheck/mce-internal.h b/arch/x86/kernel/cpu/mcheck/mce-internal.h index 547720efd923..cd74a3f00aea 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-internal.h +++ b/arch/x86/kernel/cpu/mcheck/mce-internal.h @@ -35,6 +35,7 @@ void mce_gen_pool_process(void); bool mce_gen_pool_empty(void); int mce_gen_pool_add(struct mce *mce); int mce_gen_pool_init(void); +struct llist_node *mce_gen_pool_prepare_records(void); extern int (*mce_severity)(struct mce *a, int tolerant, char **msg, bool is_excp); struct dentry *mce_get_debugfs_dir(void); @@ -81,3 +82,17 @@ static inline int apei_clear_mce(u64 record_id) #endif void mce_inject_log(struct mce *m); + +/* + * We consider records to be equivalent if bank+status+addr+misc all match. + * This is only used when the system is going down because of a fatal error + * to avoid cluttering the console log with essentially repeated information. + * In normal processing all errors seen are logged. + */ +static inline bool mce_cmp(struct mce *m1, struct mce *m2) +{ + return m1->bank != m2->bank || + m1->status != m2->status || + m1->addr != m2->addr || + m1->misc != m2->misc; +} diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index d77f3b04b277..c356f47894c9 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -161,7 +161,6 @@ void mce_log(struct mce *mce) if (!mce_gen_pool_add(mce)) irq_work_queue(&mce_irq_work); - mce->finished = 0; wmb(); for (;;) { entry = mce_log_get_idx_check(mcelog.next); @@ -194,7 +193,6 @@ void mce_log(struct mce *mce) mcelog.entry[entry].finished = 1; wmb(); - mce->finished = 1; set_bit(0, &mce_need_notify); } @@ -337,7 +335,9 @@ static void wait_for_panic(void) static void mce_panic(const char *msg, struct mce *final, char *exp) { - int i, apei_err = 0; + int apei_err = 0; + struct llist_node *pending; + struct mce_evt_llist *l; if (!fake_panic) { /* @@ -354,11 +354,10 @@ static void mce_panic(const char *msg, struct mce *final, char *exp) if (atomic_inc_return(&mce_fake_panicked) > 1) return; } + pending = mce_gen_pool_prepare_records(); /* First print corrected ones that are still unlogged */ - for (i = 0; i < MCE_LOG_LEN; i++) { - struct mce *m = &mcelog.entry[i]; - if (!(m->status & MCI_STATUS_VAL)) - continue; + llist_for_each_entry(l, pending, llnode) { + struct mce *m = &l->mce; if (!(m->status & MCI_STATUS_UC)) { print_mce(m); if (!apei_err) @@ -366,13 +365,11 @@ static void mce_panic(const char *msg, struct mce *final, char *exp) } } /* Now print uncorrected but with the final one last */ - for (i = 0; i < MCE_LOG_LEN; i++) { - struct mce *m = &mcelog.entry[i]; - if (!(m->status & MCI_STATUS_VAL)) - continue; + llist_for_each_entry(l, pending, llnode) { + struct mce *m = &l->mce; if (!(m->status & MCI_STATUS_UC)) continue; - if (!final || memcmp(m, final, sizeof(struct mce))) { + if (!final || mce_cmp(m, final)) { print_mce(m); if (!apei_err) apei_err = apei_write_mce(m); -- GitLab