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mm/hugetlb: retry to allocate for early boot hugepage allocation

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In cloud environments with massive hugepage reservations (95%+ of system
RAM), single-attempt allocation during early boot often fails due to
memory pressure.

Commit 91f386bf07 ("hugetlb: batch freeing of vmemmap pages")
intensified this by deferring page frees, increase peak memory usage
during allocation.

Introduce a retry mechanism that leverages vmemmap optimization reclaim
(~1.6% memory) when available.  Upon initial allocation failure, the
system retries until successful or no further progress is made, ensuring
reliable hugepage allocation while preserving batched vmemmap freeing
benefits.

Testing on a 256G machine allocating 252G of hugepages:
Before: 128056/129024 hugepages allocated
After:  Successfully allocated all 129024 hugepages

Link: https://lkml.kernel.org/r/20250901082052.3247-1-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Li RongQing 2025-09-01 16:20:52 +08:00 committed by Andrew Morton
parent 2b79cb3eac
commit 2a8f3f44f5
1 changed files with 22 additions and 4 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

26
mm/hugetlb.c
View file

@ -3593,10 +3593,9 @@ static unsigned long __init hugetlb_pages_alloc_boot(struct hstate *h)
unsigned long jiffies_start; unsigned long jiffies_start;
unsigned long jiffies_end; unsigned long jiffies_end;
unsigned long remaining;
job.thread_fn = hugetlb_pages_alloc_boot_node; job.thread_fn = hugetlb_pages_alloc_boot_node;
job.start = 0;
job.size = h->max_huge_pages;
/* /*
* job.max_threads is 25% of the available cpu threads by default. * job.max_threads is 25% of the available cpu threads by default.
@ -3620,10 +3619,29 @@ static unsigned long __init hugetlb_pages_alloc_boot(struct hstate *h)
} }
job.max_threads = hugepage_allocation_threads; job.max_threads = hugepage_allocation_threads;
job.min_chunk = h->max_huge_pages / hugepage_allocation_threads;
jiffies_start = jiffies; jiffies_start = jiffies;
padata_do_multithreaded(&job); do {
remaining = h->max_huge_pages - h->nr_huge_pages;
job.start = h->nr_huge_pages;
job.size = remaining;
job.min_chunk = remaining / hugepage_allocation_threads;
padata_do_multithreaded(&job);
if (h->nr_huge_pages == h->max_huge_pages)
break;
/*
* Retry only if the vmemmap optimization might have been able to free
* some memory back to the system.
*/
if (!hugetlb_vmemmap_optimizable(h))
break;
/* Continue if progress was made in last iteration */
} while (remaining != (h->max_huge_pages - h->nr_huge_pages));
jiffies_end = jiffies; jiffies_end = jiffies;
pr_info("HugeTLB: allocation took %dms with hugepage_allocation_threads=%ld\n", pr_info("HugeTLB: allocation took %dms with hugepage_allocation_threads=%ld\n",