From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx> Since balancing mode was added in bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes"), it was possible to set this mode but it wouldn't be shown in /proc/<pid>/numa_maps since there was no support for it in the mpol_to_str() helper. Furthermore, because the balancing mode sets the MPOL_F_MORON flag, it would be displayed as 'default' due a workaround introduced a few years earlier in 8790c71a18e5 ("mm/mempolicy.c: fix mempolicy printing in numa_maps"). To tidy this up we implement two changes: First we introduce a new internal flag MPOL_F_KERNEL and with it mark the kernel's internal default and fallback policies (for tasks and/or VMAs with no explicit policy set). By doing this we generalise the current special casing and replace the incorrect 'default' with the correct 'bind'. Secondly, we add a string representation and corresponding handling for MPOL_F_NUMA_BALANCING. We do this by adding a sparse mapping array of flags to names. With the sparseness being the downside, but with the advantage of generalising and removing the "policy" from flags display. End result: $ numactl -b -m 0-1,3 cat /proc/self/numa_maps 555559580000 bind=balancing:0-1,3 file=/usr/bin/cat mapped=3 active=0 N0=3 kernelpagesize_kB=16 ... v2: * Fully fix by introducing MPOL_F_KERNEL. Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx> Fixes: bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes") References: 8790c71a18e5 ("mm/mempolicy.c: fix mempolicy printing in numa_maps") Cc: Huang Ying <ying.huang@xxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> --- include/uapi/linux/mempolicy.h | 1 + mm/mempolicy.c | 44 ++++++++++++++++++++++++---------- 2 files changed, 32 insertions(+), 13 deletions(-) diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h index 1f9bb10d1a47..bcf56ce9603b 100644 --- a/include/uapi/linux/mempolicy.h +++ b/include/uapi/linux/mempolicy.h @@ -64,6 +64,7 @@ enum { #define MPOL_F_SHARED (1 << 0) /* identify shared policies */ #define MPOL_F_MOF (1 << 3) /* this policy wants migrate on fault */ #define MPOL_F_MORON (1 << 4) /* Migrate On protnone Reference On Node */ +#define MPOL_F_KERNEL (1 << 5) /* Kernel's internal policy */ /* * These bit locations are exposed in the vm.zone_reclaim_mode sysctl diff --git a/mm/mempolicy.c b/mm/mempolicy.c index aec756ae5637..8ecc6d9f100a 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -134,6 +134,7 @@ enum zone_type policy_zone = 0; static struct mempolicy default_policy = { .refcnt = ATOMIC_INIT(1), /* never free it */ .mode = MPOL_LOCAL, + .flags = MPOL_F_KERNEL, }; static struct mempolicy preferred_node_policy[MAX_NUMNODES]; @@ -3095,7 +3096,7 @@ void __init numa_policy_init(void) preferred_node_policy[nid] = (struct mempolicy) { .refcnt = ATOMIC_INIT(1), .mode = MPOL_PREFERRED, - .flags = MPOL_F_MOF | MPOL_F_MORON, + .flags = MPOL_F_MOF | MPOL_F_MORON | MPOL_F_KERNEL, .nodes = nodemask_of_node(nid), }; } @@ -3150,6 +3151,12 @@ static const char * const policy_modes[] = [MPOL_PREFERRED_MANY] = "prefer (many)", }; +static const char * const policy_flags[] = { + [ilog2(MPOL_F_STATIC_NODES)] = "static", + [ilog2(MPOL_F_RELATIVE_NODES)] = "relative", + [ilog2(MPOL_F_NUMA_BALANCING)] = "balancing", +}; + #ifdef CONFIG_TMPFS /** * mpol_parse_str - parse string to mempolicy, for tmpfs mpol mount option. @@ -3293,17 +3300,18 @@ int mpol_parse_str(char *str, struct mempolicy **mpol) * @pol: pointer to mempolicy to be formatted * * Convert @pol into a string. If @buffer is too short, truncate the string. - * Recommend a @maxlen of at least 32 for the longest mode, "interleave", the - * longest flag, "relative", and to display at least a few node ids. + * Recommend a @maxlen of at least 42 for the longest mode, "weighted + * interleave", the longest flag, "balancing", and to display at least a few + * node ids. */ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) { char *p = buffer; nodemask_t nodes = NODE_MASK_NONE; unsigned short mode = MPOL_DEFAULT; - unsigned short flags = 0; + unsigned long flags = 0; - if (pol && pol != &default_policy && !(pol->flags & MPOL_F_MORON)) { + if (!(pol->flags & MPOL_F_KERNEL)) { mode = pol->mode; flags = pol->flags; } @@ -3328,15 +3336,25 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) p += snprintf(p, maxlen, "%s", policy_modes[mode]); if (flags & MPOL_MODE_FLAGS) { - p += snprintf(p, buffer + maxlen - p, "="); + unsigned int bit, cnt = 0; - /* - * Currently, the only defined flags are mutually exclusive - */ - if (flags & MPOL_F_STATIC_NODES) - p += snprintf(p, buffer + maxlen - p, "static"); - else if (flags & MPOL_F_RELATIVE_NODES) - p += snprintf(p, buffer + maxlen - p, "relative"); + for_each_set_bit(bit, &flags, ARRAY_SIZE(policy_flags)) { + if (bit <= ilog2(MPOL_F_KERNEL)) + continue; + + if (cnt == 0) + p += snprintf(p, buffer + maxlen - p, "="); + else + p += snprintf(p, buffer + maxlen - p, ","); + + if (WARN_ON_ONCE(!policy_flags[bit])) + p += snprintf(p, buffer + maxlen - p, "bit%u", + bit); + else + p += snprintf(p, buffer + maxlen - p, + policy_flags[bit]); + cnt++; + } } if (!nodes_empty(nodes)) -- 2.44.0