From e4dcad204d3a281be6f8573e0a82648a4ad84e69 Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Sat, 30 Nov 2019 17:50:33 -0800 Subject: rss_stat: add support to detect RSS updates of external mm When a process updates the RSS of a different process, the rss_stat tracepoint appears in the context of the process doing the update. This can confuse userspace that the RSS of process doing the update is updated, while in reality a different process's RSS was updated. This issue happens in reclaim paths such as with direct reclaim or background reclaim. This patch adds more information to the tracepoint about whether the mm being updated belongs to the current process's context (curr field). We also include a hash of the mm pointer so that the process who the mm belongs to can be uniquely identified (mm_id field). Also vsprintf.c is refactored a bit to allow reuse of hashing code. [akpm@linux-foundation.org: remove unused local `str'] [joelaf@google.com: inline call to ptr_to_hashval] Link: http://lore.kernel.org/r/20191113153816.14b95acd@gandalf.local.home Link: http://lkml.kernel.org/r/20191114164622.GC233237@google.com Link: http://lkml.kernel.org/r/20191106024452.81923-1-joel@joelfernandes.org Signed-off-by: Joel Fernandes (Google) Reported-by: Ioannis Ilkos Acked-by: Petr Mladek [lib/vsprintf.c] Cc: Tim Murray Cc: Michal Hocko Cc: Carmen Jackson Cc: Mayank Gupta Cc: Daniel Colascione Cc: Steven Rostedt (VMware) Cc: Minchan Kim Cc: "Aneesh Kumar K.V" Cc: Dan Williams Cc: Jerome Glisse Cc: Matthew Wilcox Cc: Ralph Campbell Cc: Vlastimil Babka Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 8 ++++---- include/linux/string.h | 2 ++ 2 files changed, 6 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/mm.h b/include/linux/mm.h index 935383081397..b5b2523c80af 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1643,27 +1643,27 @@ static inline unsigned long get_mm_counter(struct mm_struct *mm, int member) return (unsigned long)val; } -void mm_trace_rss_stat(int member, long count); +void mm_trace_rss_stat(struct mm_struct *mm, int member, long count); static inline void add_mm_counter(struct mm_struct *mm, int member, long value) { long count = atomic_long_add_return(value, &mm->rss_stat.count[member]); - mm_trace_rss_stat(member, count); + mm_trace_rss_stat(mm, member, count); } static inline void inc_mm_counter(struct mm_struct *mm, int member) { long count = atomic_long_inc_return(&mm->rss_stat.count[member]); - mm_trace_rss_stat(member, count); + mm_trace_rss_stat(mm, member, count); } static inline void dec_mm_counter(struct mm_struct *mm, int member) { long count = atomic_long_dec_return(&mm->rss_stat.count[member]); - mm_trace_rss_stat(member, count); + mm_trace_rss_stat(mm, member, count); } /* Optimized variant when page is already known not to be PageAnon */ diff --git a/include/linux/string.h b/include/linux/string.h index b6ccdc2c7f02..02894e417565 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -216,6 +216,8 @@ int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4); extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, const void *from, size_t available); +int ptr_to_hashval(const void *ptr, unsigned long *hashval_out); + /** * strstarts - does @str start with @prefix? * @str: string to examine -- cgit v1.2.3