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Jinjiang Tu
3d702678f5
commitbda420b985("numa balancing: migrate on fault among multiple bound nodes") adds new flag MPOL_F_NUMA_BALANCING to enable NUMA balancing for MPOL_BIND memory policy. When the cpuset of tasks changes, the mempolicy of the task is rebound by mpol_rebind_nodemask(). When MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES are both not set, the behaviour of rebinding should be same whenever MPOL_F_NUMA_BALANCING is set or not. So, when an application calls set_mempolicy() with MPOL_F_NUMA_BALANCING set but both MPOL_F_STATIC_NODES and MPOL_F_RELATIVE_NODES cleared, mempolicy.w.cpuset_mems_allowed should be set to cpuset_current_mems_allowed nodemask. However, in current implementation, mpol_store_user_nodemask() wrongly returns true, causing mempolicy->w.user_nodemask to be incorrectly set to the user-specified nodemask. Later, when the cpuset of the application changes, mpol_rebind_nodemask() ends up rebinding based on the user-specified nodemask rather than the cpuset_mems_allowed nodemask as intended. I can reproduce with the following steps in qemu with 4 NUMA nodes: 1. echo '+cpuset' > /sys/fs/cgroup/cgroup.subtree_control 2. mkdir /sys/fs/cgroup/test 3. ./reproducer & 4. cat /proc/$pid/numa_maps, the task is bound to NUMA 1 5. echo $pid > /sys/fs/cgroup/test/cgroup.procs 6. cat /proc/$pid/numa_maps, the task is bound to NUMA 0 now. The reproducer code: int main() { struct bitmask *bmp; int ret; bmp = numa_parse_nodestring("1"); ret = set_mempolicy(MPOL_BIND | MPOL_F_NUMA_BALANCING, bmp->maskp, bmp->size + 1); if (ret < 0) { perror("Failed to call set_mempolicy"); exit(-1); } while (1); return 0; } If I call set_mempolicy() without MPOL_F_NUMA_BALANCING in the reproducer code. After step 5, the task is still bound to NUMA 1. To fix this, only set mempolicy->w.user_nodemask to the user-specified nodemask if MPOL_F_STATIC_NODES or MPOL_F_RELATIVE_NODES is present. Link: https://lkml.kernel.org/r/[email protected] Link: https://lkml.kernel.org/r/[email protected] Fixes:bda420b985("numa balancing: migrate on fault among multiple bound nodes") Signed-off-by: Jinjiang Tu <[email protected]> Reviewed-by: Gregory Price <[email protected]> Reviewed-by: Huang Ying <[email protected]> Acked-by: David Hildenbrand (Red Hat) <[email protected]> Cc: Alistair Popple <[email protected]> Cc: Byungchul Park <[email protected]> Cc: Joshua Hahn <[email protected]> Cc: Kefeng Wang <[email protected]> Cc: Mathew Brost <[email protected]> Cc: Mel Gorman <mgorman <[email protected]> Cc: Rakie Kim <[email protected]> Cc: Zi Yan <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
86 lines
3.0 KiB
C
86 lines
3.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* NUMA memory policies for Linux.
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* Copyright 2003,2004 Andi Kleen SuSE Labs
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*/
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#ifndef _UAPI_LINUX_MEMPOLICY_H
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#define _UAPI_LINUX_MEMPOLICY_H
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#include <linux/errno.h>
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/*
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* Both the MPOL_* mempolicy mode and the MPOL_F_* optional mode flags are
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* passed by the user to either set_mempolicy() or mbind() in an 'int' actual.
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* The MPOL_MODE_FLAGS macro determines the legal set of optional mode flags.
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*/
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/* Policies */
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enum {
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MPOL_DEFAULT,
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MPOL_PREFERRED,
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MPOL_BIND,
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MPOL_INTERLEAVE,
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MPOL_LOCAL,
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MPOL_PREFERRED_MANY,
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MPOL_WEIGHTED_INTERLEAVE,
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MPOL_MAX, /* always last member of enum */
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};
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/* Flags for set_mempolicy */
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#define MPOL_F_STATIC_NODES (1 << 15)
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#define MPOL_F_RELATIVE_NODES (1 << 14)
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#define MPOL_F_NUMA_BALANCING (1 << 13) /* Optimize with NUMA balancing if possible */
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/*
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* MPOL_MODE_FLAGS is the union of all possible optional mode flags passed to
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* either set_mempolicy() or mbind().
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*/
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#define MPOL_MODE_FLAGS \
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(MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES | MPOL_F_NUMA_BALANCING)
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/* Whether the nodemask is specified by users */
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#define MPOL_USER_NODEMASK_FLAGS (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES)
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/* Flags for get_mempolicy */
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#define MPOL_F_NODE (1<<0) /* return next IL mode instead of node mask */
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#define MPOL_F_ADDR (1<<1) /* look up vma using address */
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#define MPOL_F_MEMS_ALLOWED (1<<2) /* return allowed memories */
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/* Flags for mbind */
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#define MPOL_MF_STRICT (1<<0) /* Verify existing pages in the mapping */
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#define MPOL_MF_MOVE (1<<1) /* Move pages owned by this process to conform
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to policy */
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#define MPOL_MF_MOVE_ALL (1<<2) /* Move every page to conform to policy */
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#define MPOL_MF_LAZY (1<<3) /* UNSUPPORTED FLAG: Lazy migrate on fault */
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#define MPOL_MF_INTERNAL (1<<4) /* Internal flags start here */
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#define MPOL_MF_VALID (MPOL_MF_STRICT | \
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MPOL_MF_MOVE | \
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MPOL_MF_MOVE_ALL)
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/*
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* Internal flags that share the struct mempolicy flags word with
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* "mode flags". These flags are allocated from bit 0 up, as they
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* are never OR'ed into the mode in mempolicy API arguments.
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*/
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#define MPOL_F_SHARED (1 << 0) /* identify shared policies */
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#define MPOL_F_MOF (1 << 3) /* this policy wants migrate on fault */
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#define MPOL_F_MORON (1 << 4) /* Migrate On protnone Reference On Node */
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/*
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* Enabling zone reclaim means the page allocator will attempt to fulfill
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* the allocation request on the current node by triggering reclaim and
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* trying to shrink the current node.
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* Fallback allocations on the next candidates in the zonelist are considered
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* when reclaim fails to free up enough memory in the current node/zone.
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*
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* These bit locations are exposed in the vm.zone_reclaim_mode sysctl.
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* New bits are OK, but existing bits should not be changed.
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*/
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#define RECLAIM_ZONE (1<<0) /* Enable zone reclaim */
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#define RECLAIM_WRITE (1<<1) /* Writeout pages during reclaim */
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#define RECLAIM_UNMAP (1<<2) /* Unmap pages during reclaim */
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#endif /* _UAPI_LINUX_MEMPOLICY_H */
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