Revision 38860b2c8bb1b92f61396eb06a63adff916fc31d authored by John David Anglin on 08 November 2021, 21:48:16 UTC, committed by Helge Deller on 13 November 2021, 21:10:56 UTC
For years, there have been random segmentation faults in userspace on SMP PA-RISC machines. It occurred to me that this might be a problem in set_pte_at(). MIPS and some other architectures do cache flushes when installing PTEs with the present bit set. Here I have adapted the code in update_mmu_cache() to flush the kernel mapping when the kernel flush is deferred, or when the kernel mapping may alias with the user mapping. This simplifies calls to update_mmu_cache(). I also changed the barrier in set_pte() from a compiler barrier to a full memory barrier. I know this change is not sufficient to fix the problem. It might not be needed. I have had a few days of operation with 5.14.16 to 5.15.1 and haven't seen any random segmentation faults on rp3440 or c8000 so far. Signed-off-by: John David Anglin <dave.anglin@bell.net> Signed-off-by: Helge Deller <deller@gmx.de> Cc: stable@kernel.org # 5.12+
1 parent f0d1cfa
affinity.c
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2016 Thomas Gleixner.
* Copyright (C) 2016-2017 Christoph Hellwig.
*/
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/cpu.h>
#include <linux/sort.h>
static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
unsigned int cpus_per_vec)
{
const struct cpumask *siblmsk;
int cpu, sibl;
for ( ; cpus_per_vec > 0; ) {
cpu = cpumask_first(nmsk);
/* Should not happen, but I'm too lazy to think about it */
if (cpu >= nr_cpu_ids)
return;
cpumask_clear_cpu(cpu, nmsk);
cpumask_set_cpu(cpu, irqmsk);
cpus_per_vec--;
/* If the cpu has siblings, use them first */
siblmsk = topology_sibling_cpumask(cpu);
for (sibl = -1; cpus_per_vec > 0; ) {
sibl = cpumask_next(sibl, siblmsk);
if (sibl >= nr_cpu_ids)
break;
if (!cpumask_test_and_clear_cpu(sibl, nmsk))
continue;
cpumask_set_cpu(sibl, irqmsk);
cpus_per_vec--;
}
}
}
static cpumask_var_t *alloc_node_to_cpumask(void)
{
cpumask_var_t *masks;
int node;
masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL);
if (!masks)
return NULL;
for (node = 0; node < nr_node_ids; node++) {
if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL))
goto out_unwind;
}
return masks;
out_unwind:
while (--node >= 0)
free_cpumask_var(masks[node]);
kfree(masks);
return NULL;
}
static void free_node_to_cpumask(cpumask_var_t *masks)
{
int node;
for (node = 0; node < nr_node_ids; node++)
free_cpumask_var(masks[node]);
kfree(masks);
}
static void build_node_to_cpumask(cpumask_var_t *masks)
{
int cpu;
for_each_possible_cpu(cpu)
cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
}
static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
const struct cpumask *mask, nodemask_t *nodemsk)
{
int n, nodes = 0;
/* Calculate the number of nodes in the supplied affinity mask */
for_each_node(n) {
if (cpumask_intersects(mask, node_to_cpumask[n])) {
node_set(n, *nodemsk);
nodes++;
}
}
return nodes;
}
struct node_vectors {
unsigned id;
union {
unsigned nvectors;
unsigned ncpus;
};
};
static int ncpus_cmp_func(const void *l, const void *r)
{
const struct node_vectors *ln = l;
const struct node_vectors *rn = r;
return ln->ncpus - rn->ncpus;
}
/*
* Allocate vector number for each node, so that for each node:
*
* 1) the allocated number is >= 1
*
* 2) the allocated numbver is <= active CPU number of this node
*
* The actual allocated total vectors may be less than @numvecs when
* active total CPU number is less than @numvecs.
*
* Active CPUs means the CPUs in '@cpu_mask AND @node_to_cpumask[]'
* for each node.
*/
static void alloc_nodes_vectors(unsigned int numvecs,
cpumask_var_t *node_to_cpumask,
const struct cpumask *cpu_mask,
const nodemask_t nodemsk,
struct cpumask *nmsk,
struct node_vectors *node_vectors)
{
unsigned n, remaining_ncpus = 0;
for (n = 0; n < nr_node_ids; n++) {
node_vectors[n].id = n;
node_vectors[n].ncpus = UINT_MAX;
}
for_each_node_mask(n, nodemsk) {
unsigned ncpus;
cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
ncpus = cpumask_weight(nmsk);
if (!ncpus)
continue;
remaining_ncpus += ncpus;
node_vectors[n].ncpus = ncpus;
}
numvecs = min_t(unsigned, remaining_ncpus, numvecs);
sort(node_vectors, nr_node_ids, sizeof(node_vectors[0]),
ncpus_cmp_func, NULL);
/*
* Allocate vectors for each node according to the ratio of this
* node's nr_cpus to remaining un-assigned ncpus. 'numvecs' is
* bigger than number of active numa nodes. Always start the
* allocation from the node with minimized nr_cpus.
*
* This way guarantees that each active node gets allocated at
* least one vector, and the theory is simple: over-allocation
* is only done when this node is assigned by one vector, so
* other nodes will be allocated >= 1 vector, since 'numvecs' is
* bigger than number of numa nodes.
*
* One perfect invariant is that number of allocated vectors for
* each node is <= CPU count of this node:
*
* 1) suppose there are two nodes: A and B
* ncpu(X) is CPU count of node X
* vecs(X) is the vector count allocated to node X via this
* algorithm
*
* ncpu(A) <= ncpu(B)
* ncpu(A) + ncpu(B) = N
* vecs(A) + vecs(B) = V
*
* vecs(A) = max(1, round_down(V * ncpu(A) / N))
* vecs(B) = V - vecs(A)
*
* both N and V are integer, and 2 <= V <= N, suppose
* V = N - delta, and 0 <= delta <= N - 2
*
* 2) obviously vecs(A) <= ncpu(A) because:
*
* if vecs(A) is 1, then vecs(A) <= ncpu(A) given
* ncpu(A) >= 1
*
* otherwise,
* vecs(A) <= V * ncpu(A) / N <= ncpu(A), given V <= N
*
* 3) prove how vecs(B) <= ncpu(B):
*
* if round_down(V * ncpu(A) / N) == 0, vecs(B) won't be
* over-allocated, so vecs(B) <= ncpu(B),
*
* otherwise:
*
* vecs(A) =
* round_down(V * ncpu(A) / N) =
* round_down((N - delta) * ncpu(A) / N) =
* round_down((N * ncpu(A) - delta * ncpu(A)) / N) >=
* round_down((N * ncpu(A) - delta * N) / N) =
* cpu(A) - delta
*
* then:
*
* vecs(A) - V >= ncpu(A) - delta - V
* =>
* V - vecs(A) <= V + delta - ncpu(A)
* =>
* vecs(B) <= N - ncpu(A)
* =>
* vecs(B) <= cpu(B)
*
* For nodes >= 3, it can be thought as one node and another big
* node given that is exactly what this algorithm is implemented,
* and we always re-calculate 'remaining_ncpus' & 'numvecs', and
* finally for each node X: vecs(X) <= ncpu(X).
*
*/
for (n = 0; n < nr_node_ids; n++) {
unsigned nvectors, ncpus;
if (node_vectors[n].ncpus == UINT_MAX)
continue;
WARN_ON_ONCE(numvecs == 0);
ncpus = node_vectors[n].ncpus;
nvectors = max_t(unsigned, 1,
numvecs * ncpus / remaining_ncpus);
WARN_ON_ONCE(nvectors > ncpus);
node_vectors[n].nvectors = nvectors;
remaining_ncpus -= ncpus;
numvecs -= nvectors;
}
}
static int __irq_build_affinity_masks(unsigned int startvec,
unsigned int numvecs,
unsigned int firstvec,
cpumask_var_t *node_to_cpumask,
const struct cpumask *cpu_mask,
struct cpumask *nmsk,
struct irq_affinity_desc *masks)
{
unsigned int i, n, nodes, cpus_per_vec, extra_vecs, done = 0;
unsigned int last_affv = firstvec + numvecs;
unsigned int curvec = startvec;
nodemask_t nodemsk = NODE_MASK_NONE;
struct node_vectors *node_vectors;
if (!cpumask_weight(cpu_mask))
return 0;
nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
/*
* If the number of nodes in the mask is greater than or equal the
* number of vectors we just spread the vectors across the nodes.
*/
if (numvecs <= nodes) {
for_each_node_mask(n, nodemsk) {
cpumask_or(&masks[curvec].mask, &masks[curvec].mask,
node_to_cpumask[n]);
if (++curvec == last_affv)
curvec = firstvec;
}
return numvecs;
}
node_vectors = kcalloc(nr_node_ids,
sizeof(struct node_vectors),
GFP_KERNEL);
if (!node_vectors)
return -ENOMEM;
/* allocate vector number for each node */
alloc_nodes_vectors(numvecs, node_to_cpumask, cpu_mask,
nodemsk, nmsk, node_vectors);
for (i = 0; i < nr_node_ids; i++) {
unsigned int ncpus, v;
struct node_vectors *nv = &node_vectors[i];
if (nv->nvectors == UINT_MAX)
continue;
/* Get the cpus on this node which are in the mask */
cpumask_and(nmsk, cpu_mask, node_to_cpumask[nv->id]);
ncpus = cpumask_weight(nmsk);
if (!ncpus)
continue;
WARN_ON_ONCE(nv->nvectors > ncpus);
/* Account for rounding errors */
extra_vecs = ncpus - nv->nvectors * (ncpus / nv->nvectors);
/* Spread allocated vectors on CPUs of the current node */
for (v = 0; v < nv->nvectors; v++, curvec++) {
cpus_per_vec = ncpus / nv->nvectors;
/* Account for extra vectors to compensate rounding errors */
if (extra_vecs) {
cpus_per_vec++;
--extra_vecs;
}
/*
* wrapping has to be considered given 'startvec'
* may start anywhere
*/
if (curvec >= last_affv)
curvec = firstvec;
irq_spread_init_one(&masks[curvec].mask, nmsk,
cpus_per_vec);
}
done += nv->nvectors;
}
kfree(node_vectors);
return done;
}
/*
* build affinity in two stages:
* 1) spread present CPU on these vectors
* 2) spread other possible CPUs on these vectors
*/
static int irq_build_affinity_masks(unsigned int startvec, unsigned int numvecs,
unsigned int firstvec,
struct irq_affinity_desc *masks)
{
unsigned int curvec = startvec, nr_present = 0, nr_others = 0;
cpumask_var_t *node_to_cpumask;
cpumask_var_t nmsk, npresmsk;
int ret = -ENOMEM;
if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
return ret;
if (!zalloc_cpumask_var(&npresmsk, GFP_KERNEL))
goto fail_nmsk;
node_to_cpumask = alloc_node_to_cpumask();
if (!node_to_cpumask)
goto fail_npresmsk;
/* Stabilize the cpumasks */
cpus_read_lock();
build_node_to_cpumask(node_to_cpumask);
/* Spread on present CPUs starting from affd->pre_vectors */
ret = __irq_build_affinity_masks(curvec, numvecs, firstvec,
node_to_cpumask, cpu_present_mask,
nmsk, masks);
if (ret < 0)
goto fail_build_affinity;
nr_present = ret;
/*
* Spread on non present CPUs starting from the next vector to be
* handled. If the spreading of present CPUs already exhausted the
* vector space, assign the non present CPUs to the already spread
* out vectors.
*/
if (nr_present >= numvecs)
curvec = firstvec;
else
curvec = firstvec + nr_present;
cpumask_andnot(npresmsk, cpu_possible_mask, cpu_present_mask);
ret = __irq_build_affinity_masks(curvec, numvecs, firstvec,
node_to_cpumask, npresmsk, nmsk,
masks);
if (ret >= 0)
nr_others = ret;
fail_build_affinity:
cpus_read_unlock();
if (ret >= 0)
WARN_ON(nr_present + nr_others < numvecs);
free_node_to_cpumask(node_to_cpumask);
fail_npresmsk:
free_cpumask_var(npresmsk);
fail_nmsk:
free_cpumask_var(nmsk);
return ret < 0 ? ret : 0;
}
static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs)
{
affd->nr_sets = 1;
affd->set_size[0] = affvecs;
}
/**
* irq_create_affinity_masks - Create affinity masks for multiqueue spreading
* @nvecs: The total number of vectors
* @affd: Description of the affinity requirements
*
* Returns the irq_affinity_desc pointer or NULL if allocation failed.
*/
struct irq_affinity_desc *
irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd)
{
unsigned int affvecs, curvec, usedvecs, i;
struct irq_affinity_desc *masks = NULL;
/*
* Determine the number of vectors which need interrupt affinities
* assigned. If the pre/post request exhausts the available vectors
* then nothing to do here except for invoking the calc_sets()
* callback so the device driver can adjust to the situation.
*/
if (nvecs > affd->pre_vectors + affd->post_vectors)
affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
else
affvecs = 0;
/*
* Simple invocations do not provide a calc_sets() callback. Install
* the generic one.
*/
if (!affd->calc_sets)
affd->calc_sets = default_calc_sets;
/* Recalculate the sets */
affd->calc_sets(affd, affvecs);
if (WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS))
return NULL;
/* Nothing to assign? */
if (!affvecs)
return NULL;
masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
if (!masks)
return NULL;
/* Fill out vectors at the beginning that don't need affinity */
for (curvec = 0; curvec < affd->pre_vectors; curvec++)
cpumask_copy(&masks[curvec].mask, irq_default_affinity);
/*
* Spread on present CPUs starting from affd->pre_vectors. If we
* have multiple sets, build each sets affinity mask separately.
*/
for (i = 0, usedvecs = 0; i < affd->nr_sets; i++) {
unsigned int this_vecs = affd->set_size[i];
int ret;
ret = irq_build_affinity_masks(curvec, this_vecs,
curvec, masks);
if (ret) {
kfree(masks);
return NULL;
}
curvec += this_vecs;
usedvecs += this_vecs;
}
/* Fill out vectors at the end that don't need affinity */
if (usedvecs >= affvecs)
curvec = affd->pre_vectors + affvecs;
else
curvec = affd->pre_vectors + usedvecs;
for (; curvec < nvecs; curvec++)
cpumask_copy(&masks[curvec].mask, irq_default_affinity);
/* Mark the managed interrupts */
for (i = affd->pre_vectors; i < nvecs - affd->post_vectors; i++)
masks[i].is_managed = 1;
return masks;
}
/**
* irq_calc_affinity_vectors - Calculate the optimal number of vectors
* @minvec: The minimum number of vectors available
* @maxvec: The maximum number of vectors available
* @affd: Description of the affinity requirements
*/
unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec,
const struct irq_affinity *affd)
{
unsigned int resv = affd->pre_vectors + affd->post_vectors;
unsigned int set_vecs;
if (resv > minvec)
return 0;
if (affd->calc_sets) {
set_vecs = maxvec - resv;
} else {
cpus_read_lock();
set_vecs = cpumask_weight(cpu_possible_mask);
cpus_read_unlock();
}
return resv + min(set_vecs, maxvec - resv);
}
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