The patch titled Subject: lib/flex_proportions.c: fix corruption of denominator in flexible proportions has been removed from the -mm tree. Its filename was lib-flex_proportionsc-fix-corruption-of-denominator-in-flexible-proportions.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Jan Kara <jack@xxxxxxx> Subject: lib/flex_proportions.c: fix corruption of denominator in flexible proportions When racing with CPU hotplug, percpu_counter_sum() can return negative values for the number of observed events. This confuses fprop_new_period(), which uses unsigned type and as a result number of events is set to big *positive* number. From that moment on, things go pear shaped and can result e.g. in division by zero as denominator is later truncated to 32-bits. This bug causes a divide-by-zero oops in bdi_dirty_limit() in Borislav's 3.6.0-rc6 based kernel. Fix the issue by using a signed type in fprop_new_period(). That makes us bail out from the function without doing anything (mistakenly) thinking there are no events to age. That makes aging somewhat inaccurate but getting accurate data would be rather hard. Signed-off-by: Jan Kara <jack@xxxxxxx> Reported-by: Borislav Petkov <bp@xxxxxxxxx> Reported-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/flex_proportions.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN lib/flex_proportions.c~lib-flex_proportionsc-fix-corruption-of-denominator-in-flexible-proportions lib/flex_proportions.c --- a/lib/flex_proportions.c~lib-flex_proportionsc-fix-corruption-of-denominator-in-flexible-proportions +++ a/lib/flex_proportions.c @@ -62,7 +62,7 @@ void fprop_global_destroy(struct fprop_g */ bool fprop_new_period(struct fprop_global *p, int periods) { - u64 events; + s64 events; unsigned long flags; local_irq_save(flags); _ Patches currently in -mm which might be from jack@xxxxxxx are origin.patch linux-next.patch fs-change-return-values-from-eacces-to-eperm.patch hfsplus-add-on-disk-layout-declarations-related-to-attributes-tree.patch hfsplus-add-functionality-of-manipulating-by-records-in-attributes-tree.patch hfsplus-rework-functionality-of-getting-setting-and-deleting-of-extended-attributes.patch hfsplus-add-support-of-manipulation-by-attributes-file.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html