The quilt patch titled Date: Thu, 3 Nov 2022 06:05:13 +0000 has been removed from the -mm tree. Its filename was mm-convert-mms-rss-stats-into-percpu_counter-fix.patch This patch was dropped because an updated version will be merged ------------------------------------------------------ From: Shakeel Butt <shakeelb@xxxxxxxxxx> Date: Thu, 3 Nov 2022 06:05:13 +0000 Subject: mm: percpu_counter: use race free percpu_counter sum interface percpu_counter_sum can race with cpu offlining. Add a new interface which does not race with it and use that for check_mm(). Link: https://lkml.kernel.org/r/20221103171407.ydubp43x7tzahriq@xxxxxxxxxx Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Tested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/percpu_counter.h | 11 +++++++++++ kernel/fork.c | 2 +- lib/percpu_counter.c | 24 ++++++++++++++++++------ 3 files changed, 30 insertions(+), 7 deletions(-) --- a/include/linux/percpu_counter.h~mm-convert-mms-rss-stats-into-percpu_counter-fix +++ a/include/linux/percpu_counter.h @@ -45,6 +45,7 @@ void percpu_counter_set(struct percpu_co void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch); s64 __percpu_counter_sum(struct percpu_counter *fbc); +s64 __percpu_counter_sum_all(struct percpu_counter *fbc); int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch); void percpu_counter_sync(struct percpu_counter *fbc); @@ -85,6 +86,11 @@ static inline s64 percpu_counter_sum(str return __percpu_counter_sum(fbc); } +static inline s64 percpu_counter_sum_all(struct percpu_counter *fbc) +{ + return __percpu_counter_sum_all(fbc); +} + static inline s64 percpu_counter_read(struct percpu_counter *fbc) { return fbc->count; @@ -192,6 +198,11 @@ static inline s64 percpu_counter_sum(str { return percpu_counter_read(fbc); } + +static inline s64 percpu_counter_sum_all(struct percpu_counter *fbc) +{ + return percpu_counter_read(fbc); +} static inline bool percpu_counter_initialized(struct percpu_counter *fbc) { --- a/kernel/fork.c~mm-convert-mms-rss-stats-into-percpu_counter-fix +++ a/kernel/fork.c @@ -753,7 +753,7 @@ static void check_mm(struct mm_struct *m "Please make sure 'struct resident_page_types[]' is updated as well"); for (i = 0; i < NR_MM_COUNTERS; i++) { - long x = percpu_counter_sum(&mm->rss_stat[i]); + long x = percpu_counter_sum_all(&mm->rss_stat[i]); if (unlikely(x)) pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n", --- a/lib/percpu_counter.c~mm-convert-mms-rss-stats-into-percpu_counter-fix +++ a/lib/percpu_counter.c @@ -117,11 +117,8 @@ void percpu_counter_sync(struct percpu_c } EXPORT_SYMBOL(percpu_counter_sync); -/* - * Add up all the per-cpu counts, return the result. This is a more accurate - * but much slower version of percpu_counter_read_positive() - */ -s64 __percpu_counter_sum(struct percpu_counter *fbc) +static s64 __percpu_counter_sum_mask(struct percpu_counter *fbc, + const struct cpumask *cpu_mask) { s64 ret; int cpu; @@ -129,15 +126,30 @@ s64 __percpu_counter_sum(struct percpu_c raw_spin_lock_irqsave(&fbc->lock, flags); ret = fbc->count; - for_each_online_cpu(cpu) { + for_each_cpu(cpu, cpu_mask) { s32 *pcount = per_cpu_ptr(fbc->counters, cpu); ret += *pcount; } raw_spin_unlock_irqrestore(&fbc->lock, flags); return ret; } + +/* + * Add up all the per-cpu counts, return the result. This is a more accurate + * but much slower version of percpu_counter_read_positive() + */ +s64 __percpu_counter_sum(struct percpu_counter *fbc) +{ + return __percpu_counter_sum_mask(fbc, cpu_online_mask); +} EXPORT_SYMBOL(__percpu_counter_sum); +s64 __percpu_counter_sum_all(struct percpu_counter *fbc) +{ + return __percpu_counter_sum_mask(fbc, cpu_possible_mask); +} +EXPORT_SYMBOL(__percpu_counter_sum_all); + int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp, struct lock_class_key *key) { _ Patches currently in -mm which might be from shakeelb@xxxxxxxxxx are percpu_counter-add-percpu_counter_sum_all-interface.patch mm-convert-mms-rss-stats-into-percpu_counter.patch