• Michal Hocko's avatar
    mm, sparse: do not swamp log with huge vmemmap allocation failures · fcdaf842
    Michal Hocko authored
    While doing memory hotplug tests under heavy memory pressure we have
    noticed too many page allocation failures when allocating vmemmap memmap
    backed by huge page
    
      kworker/u3072:1: page allocation failure: order:9, mode:0x24084c0(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO)
      [...]
      Call Trace:
        dump_trace+0x59/0x310
        show_stack_log_lvl+0xea/0x170
        show_stack+0x21/0x40
        dump_stack+0x5c/0x7c
        warn_alloc_failed+0xe2/0x150
        __alloc_pages_nodemask+0x3ed/0xb20
        alloc_pages_current+0x7f/0x100
        vmemmap_alloc_block+0x79/0xb6
        __vmemmap_alloc_block_buf+0x136/0x145
        vmemmap_populate+0xd2/0x2b9
        sparse_mem_map_populate+0x23/0x30
        sparse_add_one_section+0x68/0x18e
        __add_pages+0x10a/0x1d0
        arch_add_memory+0x4a/0xc0
        add_memory_resource+0x89/0x160
        add_memory+0x6d/0xd0
        acpi_memory_device_add+0x181/0x251
        acpi_bus_attach+0xfd/0x19b
        acpi_bus_scan+0x59/0x69
        acpi_device_hotplug+0xd2/0x41f
        acpi_hotplug_work_fn+0x1a/0x23
        process_one_work+0x14e/0x410
        worker_thread+0x116/0x490
        kthread+0xbd/0xe0
        ret_from_fork+0x3f/0x70
    
    and we do see many of those because essentially every allocation fails
    for each memory section.  This is an excessive way to tell the user that
    there is nothing to really worry about because we do have a fallback
    mechanism to use base pages.  The only downside might be a performance
    degradation due to TLB pressure.
    
    This patch changes vmemmap_alloc_block() to use __GFP_NOWARN and warn
    explicitly once on the first allocation failure.  This will reduce the
    noise in the kernel log considerably, while we still have an indication
    that a performance might be impacted.
    
    [mhocko@kernel.org: forgot to git add the follow up fix]
      Link: http://lkml.kernel.org/r/20171107090635.c27thtse2lchjgvb@dhcp22.suse.cz
    Link: http://lkml.kernel.org/r/20171106092228.31098-1-mhocko@kernel.orgSigned-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
    Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
    Cc: Joe Perches <joe@perches.com>
    Cc: Vlastimil Babka <vbabka@suse.cz>
    Cc: Khalid Aziz <khalid.aziz@oracle.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    fcdaf842