• Greg Thelen's avatar
    fs, seqfile: always allow oom killer · 0f930902
    Greg Thelen authored
    Since 5cec38ac ("fs, seq_file: fallback to vmalloc instead of oom kill
    processes") seq_buf_alloc() avoids calling the oom killer for PAGE_SIZE or
    smaller allocations; but larger allocations can use the oom killer via
    vmalloc().  Thus reads of small files can return ENOMEM, but larger files
    use the oom killer to avoid ENOMEM.
    
    The effect of this bug is that reads from /proc and other virtual
    filesystems can return ENOMEM instead of the preferred behavior - oom
    killing something (possibly the calling process).  I don't know of anyone
    except Google who has noticed the issue.
    
    I suspect the fix is more needed in smaller systems where there isn't any
    reclaimable memory.  But these seem like the kinds of systems which
    probably don't use the oom killer for production situations.
    
    Memory overcommit requires use of the oom killer to select a victim
    regardless of file size.
    
    Enable oom killer for small seq_buf_alloc() allocations.
    
    Fixes: 5cec38ac ("fs, seq_file: fallback to vmalloc instead of oom kill processes")
    Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
    Signed-off-by: default avatarGreg Thelen <gthelen@google.com>
    Acked-by: default avatarEric Dumazet <edumazet@google.com>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    0f930902
seq_file.c 22.4 KB