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[2150105088, 2150105600), allocated [2150105088,= 2150106112) >> WARNING: CPU: 3 PID: 580 at mm/page_alloc.c:6877 alloc_contig_range+0= x280/0x340 Basically, you are using alloc_contig_range() to allocate a compound page= that can be allocated from buddy allocator, since order is < MAX_ORDER. What is the use case? Why is alloc_contig_range() used? >> >> alloc_contig_range() marks pageblocks of the requested pfn range to be= >> isolated, migrate these pages if they are in use and will be freed to >> MIGRATE_ISOLATED freelist. >> >> Suppose two alloc_contig_range() calls at the same time and the reques= ted >> pfn range are [0x80280000, 0x80280200) and [0x80280200, 0x80280400) >> respectively. Suppose the two memory range are in use, then >> alloc_contig_range() will migrate and free these pages to MIGRATE_ISOL= ATED >> freelist. __free_one_page() will merge MIGRATE_ISOLATE buddy to larger= >> buddy, resulting in a MAX_ORDER buddy. Finally, find_large_buddy() in >> alloc_contig_range() returns a MAX_ORDER buddy and results in WARNING.= >> >> To fix it, call free_contig_range() to free the excess pfn range. > > This has been in mm-hotfixes for a month without issue. Is there any > reviewer interest? > >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -6528,7 +6528,8 @@ int alloc_contig_range_noprof(unsigned long star= t, unsigned long end, >> goto done; >> } >> >> - if (!(gfp_mask & __GFP_COMP)) { >> + if (!(gfp_mask & __GFP_COMP) || >> + (is_power_of_2(end - start) && ilog2(end - start) < MAX_PAGE_ORDER)= ) { >> split_free_pages(cc.freepages, gfp_mask); This does not look right to me. When a compound page is requested, alloc_contig_range() should give a compound page, but split_free_pages() will make the free page as a list of contiguous order-0 pages. I do not think we should keep this patch. Jinjiang, let me know if I miss anything. >> >> /* Free head and tail (if any) */ >> @@ -6536,7 +6537,15 @@ int alloc_contig_range_noprof(unsigned long sta= rt, unsigned long end, >> free_contig_range(outer_start, start - outer_start); >> if (end !=3D outer_end) >> free_contig_range(end, outer_end - end); >> - } else if (start =3D=3D outer_start && end =3D=3D outer_end && is_po= wer_of_2(end - start)) { >> + >> + outer_start =3D start; >> + outer_end =3D end; >> + >> + if (!(gfp_mask & __GFP_COMP)) >> + goto done; >> + } >> + >> + if (start =3D=3D outer_start && end =3D=3D outer_end && is_power_of_= 2(end - start)) { >> struct page *head =3D pfn_to_page(start); >> int order =3D ilog2(end - start); >> Best Regards, Yan, Zi