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    SubjectRe: [PATCH] mm, sparse: do not swamp log with huge vmemmap allocation failures
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    On Mon, 2017-11-06 at 12:35 -0500, Johannes Weiner wrote:
    > On Mon, Nov 06, 2017 at 10:22:28AM +0100, Michal Hocko wrote:
    > > From: Michal Hocko <mhocko@suse.com>
    > >
    > > While doing a memory hotplug tests under a heavy memory pressure we have
    > > noticed too many page allocation failures when allocating vmemmap memmap
    > > backed by huge page
    > > [146792.281354] kworker/u3072:1: page allocation failure: order:9, mode:0x24084c0(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO)
    > > [...]
    > > [146792.281394] Call Trace:
    > > [146792.281430] [<ffffffff81019a99>] dump_trace+0x59/0x310
    > > [146792.281436] [<ffffffff81019e3a>] show_stack_log_lvl+0xea/0x170
    > > [146792.281440] [<ffffffff8101abc1>] show_stack+0x21/0x40
    > > [146792.281448] [<ffffffff8130f040>] dump_stack+0x5c/0x7c
    > > [146792.281464] [<ffffffff8118c982>] warn_alloc_failed+0xe2/0x150
    > > [146792.281471] [<ffffffff8118cddd>] __alloc_pages_nodemask+0x3ed/0xb20
    > > [146792.281489] [<ffffffff811d3aaf>] alloc_pages_current+0x7f/0x100
    > > [146792.281503] [<ffffffff815dfa2c>] vmemmap_alloc_block+0x79/0xb6
    > > [146792.281510] [<ffffffff815dfbd3>] __vmemmap_alloc_block_buf+0x136/0x145
    > > [146792.281524] [<ffffffff815dd0c5>] vmemmap_populate+0xd2/0x2b9
    > > [146792.281529] [<ffffffff815dffd9>] sparse_mem_map_populate+0x23/0x30
    > > [146792.281532] [<ffffffff815df88d>] sparse_add_one_section+0x68/0x18e
    > > [146792.281537] [<ffffffff815d9f5a>] __add_pages+0x10a/0x1d0
    > > [146792.281553] [<ffffffff8106249a>] arch_add_memory+0x4a/0xc0
    > > [146792.281559] [<ffffffff815da1f9>] add_memory_resource+0x89/0x160
    > > [146792.281564] [<ffffffff815da33d>] add_memory+0x6d/0xd0
    > > [146792.281585] [<ffffffff813d36c4>] acpi_memory_device_add+0x181/0x251
    > > [146792.281597] [<ffffffff813946e5>] acpi_bus_attach+0xfd/0x19b
    > > [146792.281602] [<ffffffff81394866>] acpi_bus_scan+0x59/0x69
    > > [146792.281604] [<ffffffff813949de>] acpi_device_hotplug+0xd2/0x41f
    > > [146792.281608] [<ffffffff8138db67>] acpi_hotplug_work_fn+0x1a/0x23
    > > [146792.281623] [<ffffffff81093cee>] process_one_work+0x14e/0x410
    > > [146792.281630] [<ffffffff81094546>] worker_thread+0x116/0x490
    > > [146792.281637] [<ffffffff810999ed>] kthread+0xbd/0xe0
    > > [146792.281651] [<ffffffff815e4e7f>] ret_from_fork+0x3f/0x70
    > >
    > > and we do see many of those because essentially every the allocation
    > > failes for each memory section. This is overly excessive way to tell
    > > 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.
    > >
    > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
    > > Signed-off-by: Michal Hocko <mhocko@suse.com>
    > > ---
    > > Hi,
    > > this has somehow fell of my radar completely. The patch is essentially
    > > what Johannes suggested [1] so I have added his s-o-b and added the
    > > changelog into it.
    >
    > Looks good to me.

    I think it'd be better to change the ratelimit state
    to something like once a minute
    ---
    mm/page_alloc.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 82e6d2c914ab..af3f92beec04 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -3269,8 +3269,7 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
    {
    struct va_format vaf;
    va_list args;
    - static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL,
    - DEFAULT_RATELIMIT_BURST);
    + static DEFINE_RATELIMIT_STATE(nopage_rs, HZ * 60, 1);

    if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs))
    return; mm/page_alloc.c | 3 +--
    1 file changed, 1 insertion(+), 2 deletions(-)

    diff --git a/mm/page_alloc.c b/mm/page_alloc.c
    index 82e6d2c914ab..af3f92beec04 100644
    --- a/mm/page_alloc.c
    +++ b/mm/page_alloc.c
    @@ -3269,8 +3269,7 @@ void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)
    {
    struct va_format vaf;
    va_list args;
    - static DEFINE_RATELIMIT_STATE(nopage_rs, DEFAULT_RATELIMIT_INTERVAL,
    - DEFAULT_RATELIMIT_BURST);
    + static DEFINE_RATELIMIT_STATE(nopage_rs, HZ * 60, 1);

    if ((gfp_mask & __GFP_NOWARN) || !__ratelimit(&nopage_rs))
    return;
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