• Michal Hocko's avatar
    jbd2: get rid of superfluous __GFP_REPEAT · f2db1971
    Michal Hocko authored
    jbd2_alloc is explicit about its allocation preferences wrt.  the
    allocation size.  Sub page allocations go to the slab allocator and
    larger are using either the page allocator or vmalloc.  This is all good
    but the logic is unnecessarily complex.
    
    1) as per Ted, the vmalloc fallback is a left-over:
    
     : jbd2_alloc is only passed in the bh->b_size, which can't be PAGE_SIZE, so
     : the code path that calls vmalloc() should never get called.  When we
     : conveted jbd2_alloc() to suppor sub-page size allocations in commit
     : d2eecb03, there was an assumption that it could be called with a size
     : greater than PAGE_SIZE, but that's certaily not true today.
    
    Moreover vmalloc allocation might even lead to a deadlock because the
    callers expect GFP_NOFS context while vmalloc is GFP_KERNEL.
    
    2) __GFP_REPEAT for requests <= PAGE_ALLOC_COSTLY_ORDER is ignored
       since the flag was introduced.
    
    Let's simplify the code flow and use the slab allocator for sub-page
    requests and the page allocator for others.  Even though order > 0 is
    not currently used as per above leave that option open.
    
    Link: http://lkml.kernel.org/r/1464599699-30131-18-git-send-email-mhocko@kernel.orgSigned-off-by: default avatarMichal Hocko <mhocko@suse.com>
    Reviewed-by: default avatarJan Kara <jack@suse.cz>
    Cc: "Theodore Ts'o" <tytso@mit.edu>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    f2db1971
journal.c 74.8 KB