Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Qian Cai
authored
Commit f1dd2cd1 ("mm, memory_hotplug: do not associate hotadded memory to zones until online") introduced move_pfn_range_to_zone() which calls memmap_init_zone() during onlining a memory block. memmap_init_zone() will reset pagetype flags and makes migrate type to be MOVABLE. However, in __offline_pages(), it also call undo_isolate_page_range() after offline_isolated_pages() to do the same thing. Due to commit 2ce13640 ("mm: __first_valid_page skip over offline pages") changed __first_valid_page() to skip offline pages, undo_isolate_page_range() here just waste CPU cycles looping around the offlining PFN range while doing nothing, because __first_valid_page() will return NULL as offline_isolated_pages() has already marked all memory sections within the pfn range as offline via offline_mem_sections(). Also, after calling the "useless" undo_isolate_page_range() here, it reaches the point of no returning by notifying MEM_OFFLINE. Those pages will be marked as MIGRATE_MOVABLE again once onlining. The only thing left to do is to decrease the number of isolated pageblocks zone counter which would make some paths of the page allocation slower that the above commit introduced. Even if alloc_contig_range() can be used to isolate 16GB-hugetlb pages on ppc64, an "int" should still be enough to represent the number of pageblocks there. Fix an incorrect comment along the way. [cai@lca.pw: v4] Link: http://lkml.kernel.org/r/20190314150641.59358-1-cai@lca.pw Link: http://lkml.kernel.org/r/20190313143133.46200-1-cai@lca.pw Fixes: 2ce13640 ("mm: __first_valid_page skip over offline pages") Signed-off-by:Qian Cai <cai@lca.pw> Acked-by:
Michal Hocko <mhocko@suse.com> Reviewed-by:
Oscar Salvador <osalvador@suse.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: <stable@vger.kernel.org> [4.13+] Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
| Name | Last commit | Last update |
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| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
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| lib | ||
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| net | ||
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| virt | ||
| .clang-format | ||
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