From: Michal Hocko <mhocko@xxxxxxxx> Subject: mm, sparse: do not swamp log with huge vmemmap allocation failures 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 [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 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@xxxxxxxxxx: forgot to git add the follow up fix] Link: http://lkml.kernel.org/r/20171107090635.c27thtse2lchjgvb@xxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/20171106092228.31098-1-mhocko@xxxxxxxxxx Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Khalid Aziz <khalid.aziz@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/mm/init_64.c | 1 - mm/sparse-vmemmap.c | 12 ++++++++++-- 2 files changed, 10 insertions(+), 3 deletions(-) diff -puN arch/x86/mm/init_64.c~mm-sparse-do-not-swamp-log-with-huge-vmemmap-allocation-failures arch/x86/mm/init_64.c --- a/arch/x86/mm/init_64.c~mm-sparse-do-not-swamp-log-with-huge-vmemmap-allocation-failures +++ a/arch/x86/mm/init_64.c @@ -1405,7 +1405,6 @@ static int __meminit vmemmap_populate_hu vmemmap_verify((pte_t *)pmd, node, addr, next); continue; } - pr_warn_once("vmemmap: falling back to regular page backing\n"); if (vmemmap_populate_basepages(addr, next, node)) return -ENOMEM; } diff -puN mm/sparse-vmemmap.c~mm-sparse-do-not-swamp-log-with-huge-vmemmap-allocation-failures mm/sparse-vmemmap.c --- a/mm/sparse-vmemmap.c~mm-sparse-do-not-swamp-log-with-huge-vmemmap-allocation-failures +++ a/mm/sparse-vmemmap.c @@ -53,12 +53,20 @@ void * __meminit vmemmap_alloc_block(uns { /* If the main allocator is up use that, fallback to bootmem. */ if (slab_is_available()) { + gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN; + int order = get_order(size); + static bool warned; struct page *page; - page = alloc_pages_node(node, GFP_KERNEL | __GFP_RETRY_MAYFAIL, - get_order(size)); + page = alloc_pages_node(node, gfp_mask, order); if (page) return page_address(page); + + if (!warned) { + warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL, + "vmemmap alloc failure: order:%u", order); + warned = true; + } return NULL; } else return __earlyonly_bootmem_alloc(node, size, size, _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
