Re: [PATCH 4.19] x86/mm: add cond_resched() in _set_memory_array() and set_memory_array_wb()

On Fri, Nov 26, 2021 at 03:32:26PM +0800, Yang Wei wrote:

From: Yang Wei yang.wei@linux.alibaba.com

We found _set_memory_array() and set_memory_array_wb() takes more than 500ms in kernel space in the following scenario. So use this patch to trigger schedule for each page, to avoid other threads getting stuck.

0xffffffff810a34d2 find_next_iomem_res  ([kernel.kallsyms])
0xffffffff810a3d40 walk_system_ram_range  ([kernel.kallsyms])
0xffffffff810772ca pat_pagerange_is_ram  ([kernel.kallsyms])
0xffffffff8107796f reserve_memtype  ([kernel.kallsyms])
0xffffffff81075e98 _set_memory_array  ([kernel.kallsyms])
0xffffffffc0ef6083 nv_alloc_system_pages  [nvidia] ([kernel.kallsyms])

0xffffffff810a34d2 find_next_iomem_res  ([kernel.kallsyms])
0xffffffff810a3d40 walk_system_ram_range  ([kernel.kallsyms])
0xffffffff810772ca pat_pagerange_is_ram  ([kernel.kallsyms])
0xffffffff8107745a free_memtype.part.7  ([kernel.kallsyms])
0xffffffff8107606e set_memory_array_wb  ([kernel.kallsyms])
0xffffffffc0ef6291 nv_free_system_pages  [nvidia]([kernel.kallsyms])

Signed-off-by: Yang Wei yang.wei@linux.alibaba.com Tested-by: Yang Wei yang.wei@linux.alibaba.com

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arch/x86/mm/pageattr.c | 2 ++ 1 file changed, 2 insertions(+)

Why is this 4.19-only?

What commit in Linus's tree resolved this issue?

confused,

greg k-h