Commit df529cab authored by Jaewon Kim's avatar Jaewon Kim Committed by Linus Torvalds
Browse files

mm: mmap: add trace point of vm_unmapped_area

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

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.

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

[ prefix address printk with 0x, per Matthew]
Signed-off-by: default avatarJaewon Kim <>
Signed-off-by: default avatarAndrew Morton <>
Cc: Borislav Petkov <>
Cc: Matthew Wilcox (Oracle) <>
Cc: Michel Lespinasse <>
Cc: Vlastimil Babka <>

Signed-off-by: default avatarLinus Torvalds <>
parent baceaf1c
/* SPDX-License-Identifier: GPL-2.0 */
#define TRACE_SYSTEM mmap
#if !defined(_TRACE_MMAP_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_MMAP_H
#include <linux/tracepoint.h>
TP_PROTO(unsigned long addr, struct vm_unmapped_area_info *info),
TP_ARGS(addr, info),
__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)
__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,
/* This part must be outside protection */
#include <trace/define_trace.h>
......@@ -53,6 +53,9 @@
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#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);
return unmapped_area(info);
addr = unmapped_area(info);
trace_vm_unmapped_area(addr, info);
return addr;
#ifndef arch_get_mmap_end
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment