Messages in this thread Patch in this message | | | Date | Wed, 4 Nov 2015 12:32:14 -0800 (PST) | From | David Rientjes <> | Subject | [patch] mm, oom: add comment for why oom_adj exists |
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/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> --- fs/proc/base.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/fs/proc/base.c b/fs/proc/base.c --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -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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