mm, oom: add comment for why oom_adj exists (b72bdfa7) · Commits · 戴 / test

/proc/pid/oom_adj exists solely to avoid breaking existing userspace binaries that write to the tunable. Add a comment in the only possible location within the kernel tree to describe the situation and motivation for keeping it around. Signed-off-by:

David Rientjes <rientjes@google.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/base.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -1032,6 +1032,16 @@ static ssize_t oom_adj_read(struct file file, char __user buf, size_t count,
		return simple_read_from_buffer(buf, count, ppos, buffer, len);
		}

		/*
		* /proc/pid/oom_adj exists solely for backwards compatibility with previous
		* kernels. The effective policy is defined by oom_score_adj, which has a
		* different scale: oom_adj grew exponentially and oom_score_adj grows linearly.
		* Values written to oom_adj are simply mapped linearly to oom_score_adj.
		* Processes that become oom disabled via oom_adj will still be oom disabled
		* with this implementation.
		*
		* oom_adj cannot be removed since existing userspace binaries use it.
		*/
		static ssize_t oom_adj_write(struct file file, const char __user buf,
		size_t count, loff_t *ppos)
		{

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