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rss_stat: add support to detect RSS updates of external mm

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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) <joel@joelfernandes.org>
Reported-by: Ioannis Ilkos <ilkos@google.com>
Acked-by: Petr Mladek <pmladek@suse.com>	[lib/vsprintf.c]
Cc: Tim Murray <timmurray@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Carmen Jackson <carmenjackson@google.com>
Cc: Mayank Gupta <mayankgupta@google.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joel Fernandes (Google)
2019-11-30 17:50:33 -08:00
committed by Linus Torvalds
parent b3d1411b67
commit e4dcad204d
5 changed files with 69 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
include/trace/events/kmem.h
View File

@@ -316,24 +316,50 @@ TRACE_EVENT(mm_page_alloc_extfrag,
__entry->change_ownership)
);
/*
* Required for uniquely and securely identifying mm in rss_stat tracepoint.
*/
#ifndef __PTR_TO_HASHVAL
static unsigned int __maybe_unused mm_ptr_to_hash(const void *ptr)
{
int ret;
unsigned long hashval;
ret = ptr_to_hashval(ptr, &hashval);
if (ret)
return 0;
/* The hashed value is only 32-bit */
return (unsigned int)hashval;
}
#define __PTR_TO_HASHVAL
#endif
TRACE_EVENT(rss_stat,
TP_PROTO(int member,
TP_PROTO(struct mm_struct *mm,
int member,
long count),
TP_ARGS(member, count),
TP_ARGS(mm, member, count),
TP_STRUCT__entry(
__field(unsigned int, mm_id)
__field(unsigned int, curr)
__field(int, member)
__field(long, size)
),
TP_fast_assign(
__entry->mm_id = mm_ptr_to_hash(mm);
__entry->curr = !!(current->mm == mm);
__entry->member = member;
__entry->size = (count << PAGE_SHIFT);
),
TP_printk("member=%d size=%ldB",
TP_printk("mm_id=%u curr=%d member=%d size=%ldB",
__entry->mm_id,
__entry->curr,
__entry->member,
__entry->size)
);