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mm: mmap: add trace point of vm_unmapped_area

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Even on 64 bit kernel, the mmap failure can happen for a 32 bit task.
Virtual memory space shortage of a task on mmap is reported to userspace
as -ENOMEM.  It can be confused as physical memory shortage of overall
system.

The vm_unmapped_area can be called to by some drivers or other kernel core
system like filesystem.  In my platform, GPU driver calls to
vm_unmapped_area and the driver returns -ENOMEM even in GPU side shortage.
It can be hard to distinguish which code layer returns the -ENOMEM.

Create mmap trace file and add trace point of vm_unmapped_area.

i.e.)
277.156599: vm_unmapped_area: addr=77e0d03000 err=0 total_vm=0x17014b flags=0x1 len=0x400000 lo=0x8000 hi=0x7878c27000 mask=0x0 ofs=0x1
342.838740: vm_unmapped_area: addr=0 err=-12 total_vm=0xffb08 flags=0x0 len=0x100000 lo=0x40000000 hi=0xfffff000 mask=0x0 ofs=0x22

[akpm@linux-foundation.org: prefix address printk with 0x, per Matthew]
Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/r/20200320055823.27089-3-jaewon31.kim@samsung.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jaewon Kim 2020-04-01 21:09:13 -07:00 committed by Linus Torvalds
parent baceaf1c8b
commit df529cabb7
2 changed files with 58 additions and 2 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

48
include/trace/events/mmap.h Normal file
View file

@ -0,0 +1,48 @@
/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM mmap
#if !defined(_TRACE_MMAP_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_MMAP_H
#include <linux/tracepoint.h>
TRACE_EVENT(vm_unmapped_area,
TP_PROTO(unsigned long addr, struct vm_unmapped_area_info *info),
TP_ARGS(addr, info),
TP_STRUCT__entry(
__field(unsigned long, addr)
__field(unsigned long, total_vm)
__field(unsigned long, flags)
__field(unsigned long, length)
__field(unsigned long, low_limit)
__field(unsigned long, high_limit)
__field(unsigned long, align_mask)
__field(unsigned long, align_offset)
),
TP_fast_assign(
__entry->addr = addr;
__entry->total_vm = current->mm->total_vm;
__entry->flags = info->flags;
__entry->length = info->length;
__entry->low_limit = info->low_limit;
__entry->high_limit = info->high_limit;
__entry->align_mask = info->align_mask;
__entry->align_offset = info->align_offset;
),
TP_printk("addr=0x%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
IS_ERR_VALUE(__entry->addr) ? 0 : __entry->addr,
IS_ERR_VALUE(__entry->addr) ? __entry->addr : 0,
__entry->total_vm, __entry->flags, __entry->length,
__entry->low_limit, __entry->high_limit, __entry->align_mask,
__entry->align_offset)
);
#endif
/* This part must be outside protection */
#include <trace/define_trace.h>

12
mm/mmap.c
View file

@ -53,6 +53,9 @@
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#define CREATE_TRACE_POINTS
#include <trace/events/mmap.h>
#include "internal.h"
#ifndef arch_mmap_check
@ -2061,10 +2064,15 @@ static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
*/
unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
{
unsigned long addr;
if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
return unmapped_area_topdown(info);
addr = unmapped_area_topdown(info);
else
return unmapped_area(info);
addr = unmapped_area(info);
trace_vm_unmapped_area(addr, info);
return addr;
}
#ifndef arch_get_mmap_end