Re: [PATCH] mm/mempolicy.c: forbid static or relative flags for local NUMA mode
From: Vlastimil Babka <hidden>
Date: 2016-09-20 15:12:29
Also in:
linux-api, linux-man, lkml
[CC += linux-api@vger.kernel.org]
Since this is a kernel-user-space API change, please CC linux-api@. The
kernel source file Documentation/SubmitChecklist notes that all Linux kernel
patches that change userspace interfaces should be CCed to
linux-api@vger.kernel.org, so that the various parties who are interested in API
changes are informed. For further information, see
https://www.kernel.org/doc/man-pages/linux-api-ml.html
I think man page should document the change? Also I noticed that MPOL_NUMA
itself is missing in the man page...
On 09/18/2016 01:29 PM, Piotr Kwapulinski wrote:The MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES flags are irrelevant when setting them for MPOL_LOCAL NUMA memory policy via set_mempolicy. Return the "invalid argument" from set_mempolicy whenever any of these flags is passed along with MPOL_LOCAL. It is consistent with MPOL_PREFERRED passed with empty nodemask. It also slightly shortens the execution time in paths where these flags are used e.g. when trying to rebind the NUMA nodes for changes in cgroups cpuset mems (mpol_rebind_preferred()) or when just printing the mempolicy structure (/proc/PID/numa_maps).
Hmm not sure I understand. How does change in mpol_new() affect mpol_rebind_preferred()? Vlastimil
quoted hunk ↗ jump to hunk
Isolated tests done. Signed-off-by: Piotr Kwapulinski <redacted> --- mm/mempolicy.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 2da72a5..27b07d1 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c@@ -276,7 +276,9 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, return ERR_PTR(-EINVAL); } } else if (mode == MPOL_LOCAL) { - if (!nodes_empty(*nodes)) + if (!nodes_empty(*nodes) || + (flags & MPOL_F_STATIC_NODES) || + (flags & MPOL_F_RELATIVE_NODES)) return ERR_PTR(-EINVAL); mode = MPOL_PREFERRED; } else if (nodes_empty(*nodes))
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