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An application is suspected of having memory leak when its memory consumption is high and keeps increasing. There are several commonly used memory allocators: slab, cma, vmalloc, etc. The memory leak identification can be sped up if the page information allocated by an allocator can be analyzed separately. This patch provides supports for memory allocator labelling for slab, vmalloc, and cma. The pages allocated by slab and cma can be confirmed from the "PFN" line according to the kernel codes, and the label of the vmalloc allocator can be obtained by analyzing the stack trace. Thanks for Vlastimil Babka's constructive suggestions. Based on Yinan Zhang's study, the call chain of vmalloc() is vmalloc() -> ... -> __vmalloc_node_range() -> __vmalloc_area_node(). __vmalloc_area_node() requests memory through the interface of buddy allocation system. In the current version, __vmalloc_area_node() uses four interfaces: alloc_pages_bulk_array_mempolicy(), alloc_pages_bulk_array_node(), alloc_pages() and alloc_pages_node(). By disassembling the code, we find that __vmalloc_area_node() is expanded in __vmalloc_node_range(). So __vmalloc_area_node is not in the stack trace. On the test machine, the stack trace of pages allocated by vmalloc has the following four forms: __alloc_pages_bulk+0x230/0x6a0 __vmalloc_node_range+0x19c/0x598 alloc_pages_bulk_array_mempolicy+0xbc/0x278 __vmalloc_node_range+0x1e8/0x598 __alloc_pages+0x160/0x2b0 __vmalloc_node_range+0x234/0x598 alloc_pages+0xac/0x150 __vmalloc_node_range+0x44c/0x598 Therefore, in two consecutive lines of stacktrace, if the first line contains the word "alloc_pages" and the second line contains the word "__vmalloc_node_range", it can be determined that the page is allocated by vmalloc. And the function offset and size are not the same on different machines, so there is no need to match them. At the same time, this patch updates the --cull and --sort options to support allocator-based merge statistics and sorting. The added functions are fully compatible with the original work. When using, you can use "allocator", or abbreviated as "ator". Relevant updates have also been made in the documentation(Documentation/vm/page_owner.rst). Example: ./page_owner_sort <input> <output> --cull=st,pid,name,allocator ./page_owner_sort <input> <output> --sort=ator,pid,name This work is coauthored by Jiajian Ye, Yinan Zhang, Shenghong Han, Chongxi Zhao, Yuhong Feng and Yongqiang Liu. Link: https://lkml.kernel.org/r/20220410132932.9402-1-caoyixuan2019@email.szu.edu.cn Signed-off-by: Yixuan Cao <caoyixuan2019@email.szu.edu.cn> Cc: Chongxi Zhao <zhaochongxi2019@email.szu.edu.cn> Cc: Haowen Bai <baihaowen@meizu.com> Cc: Jiajian Ye <yejiajian2018@email.szu.edu.cn> Cc: Sean Anderson <seanga2@gmail.com> Cc: Shenghong Han <hanshenghong2019@email.szu.edu.cn> Cc: Yinan Zhang <zhangyinan2019@email.szu.edu.cn> Cc: Yongqiang Liu <liuyongqiang13@huawei.com> Cc: Yuhong Feng <yuhongf@szu.edu.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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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.