Re: [PATCH v4 20/36] mm/page_ext: enable early_page_ext when CONFIG_MEM_ALLOC_PROFILING_DEBUG=y
From: Vlastimil Babka <hidden>
Date: 2024-02-27 10:17:32
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cgroups, linux-arch, linux-doc, linux-fsdevel, linux-iommu, linux-mm, lkml
On 2/21/24 20:40, Suren Baghdasaryan wrote:
For all page allocations to be tagged, page_ext has to be initialized before the first page allocation. Early tasks allocate their stacks using page allocator before alloc_node_page_ext() initializes page_ext area, unless early_page_ext is enabled. Therefore these allocations will generate a warning when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled. Enable early_page_ext whenever CONFIG_MEM_ALLOC_PROFILING_DEBUG=y to ensure page_ext initialization prior to any page allocation. This will have all the negative effects associated with early_page_ext, such as possible longer boot time, therefore we enable it only when debugging with CONFIG_MEM_ALLOC_PROFILING_DEBUG enabled and not universally for CONFIG_MEM_ALLOC_PROFILING. Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <redacted>
quoted hunk ↗ jump to hunk
--- mm/page_ext.c | 9 +++++++++ 1 file changed, 9 insertions(+)diff --git a/mm/page_ext.c b/mm/page_ext.c index 3c58fe8a24df..e7d8f1a5589e 100644 --- a/mm/page_ext.c +++ b/mm/page_ext.c@@ -95,7 +95,16 @@ unsigned long page_ext_size; static unsigned long total_usage; +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG +/* + * To ensure correct allocation tagging for pages, page_ext should be available + * before the first page allocation. Otherwise early task stacks will be + * allocated before page_ext initialization and missing tags will be flagged. + */ +bool early_page_ext __meminitdata = true; +#else bool early_page_ext __meminitdata; +#endif static int __init setup_early_page_ext(char *str) { early_page_ext = true;