• Jaewon Kim's avatar
    mm: mmap: add trace point of vm_unmapped_area · df529cab
    Jaewon Kim authored
    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: default avatarJaewon Kim <jaewon31.kim@samsung.com>
    Signed-off-by: default avatarAndrew 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.comSigned-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    df529cab
mmap.h 1.37 KB