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| author | Jaewon Kim <jaewon31.kim@samsung.com> | 2020-04-01 21:09:13 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-04-02 09:35:30 -0700 |
| commit | df529cabb7a2553bbeb7bab725776f62fdcec972 (patch) | |
| tree | 8e5e791a94c194acc9667059175ae55b2182dbce /mm/mmap.c | |
| parent | baceaf1c8b99080ae5274d7262df8b09fa981762 (diff) | |
| download | lwn-df529cabb7a2553bbeb7bab725776f62fdcec972.tar.gz lwn-df529cabb7a2553bbeb7bab725776f62fdcec972.zip | |
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
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>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index ba990c20ecc2..94ae18398c59 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -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 @@ found_highest: */ 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 |