122e093c17
On systems with memory nodes sorted in descending order, for instance Dell Precision WorkStation T5500, the struct pages for higher PFNs and respectively lower nodes, could be overwritten by the initialization of struct pages corresponding to the holes in the memory sections. For example for the below memory layout [ 0.245624] Early memory node ranges [ 0.248496] node 1: [mem 0x0000000000001000-0x0000000000090fff] [ 0.251376] node 1: [mem 0x0000000000100000-0x00000000dbdf8fff] [ 0.254256] node 1: [mem 0x0000000100000000-0x0000001423ffffff] [ 0.257144] node 0: [mem 0x0000001424000000-0x0000002023ffffff] the range 0x1424000000 - 0x1428000000 in the beginning of node 0 starts in the middle of a section and will be considered as a hole during the initialization of the last section in node 1. The wrong initialization of the memory map causes panic on boot when CONFIG_DEBUG_VM is enabled. Reorder loop order of the memory map initialization so that the outer loop will always iterate over populated memory regions in the ascending order and the inner loop will select the zone corresponding to the PFN range. This way initialization of the struct pages for the memory holes will be always done for the ranges that are actually not populated. [akpm@linux-foundation.org: coding style fixes] Link: https://lkml.kernel.org/r/YNXlMqBbL+tBG7yq@kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=213073 Link: https://lkml.kernel.org/r/20210624062305.10940-1-rppt@kernel.org Fixes: 0740a50b9baa ("mm/page_alloc.c: refactor initialization of struct page for holes in memory layout") Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Cc: Boris Petkov <bp@alien8.de> Cc: Robert Shteynfeld <robert.shteynfeld@gmail.com> Cc: Baoquan He <bhe@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.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
============
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.