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Bharata has noticed that onlining a newly added memory doesn't increase the total memory, pointing to commitf7f99100d8("mm: stop zeroing memory during allocation in vmemmap") as a culprit. This commit has changed the way how the memory for memmaps is initialized and moves it from the allocation time to the initialization time. This works properly for the early memmap init path. It doesn't work for the memory hotplug though because we need to mark page as reserved when the sparsemem section is created and later initialize it completely during onlining. memmap_init_zone is called in the early stage of onlining. With the current code it calls __init_single_page and as such it clears up the whole stage and therefore online_pages_range skips those pages. Fix this by skipping mm_zero_struct_page in __init_single_page for memory hotplug path. This is quite uggly but unifying both early init and memory hotplug init paths is a large project. Make sure we plug the regression at least. Link: http://lkml.kernel.org/r/20180130101141.GW21609@dhcp22.suse.cz Fixes:f7f99100d8("mm: stop zeroing memory during allocation in vmemmap") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Tested-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com> Cc: Steven Sistare <steven.sistare@oracle.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Bob Picco <bob.picco@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.