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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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eff3860bbf
Commit66ee620f06("idr: Permit any valid kernel pointer to be stored") changed the radix tree lookup so that it stops when reaching the bottom of the tree. However, the condition was added in the wrong place, making it possible to return retry entries to the caller. Reorder the tests to check for the retry entry before checking whether we're at the bottom of the tree. The retry entry should never be found in the tree root, so it's safe to defer the check until the end of the loop. Add a regression test to the test-suite to be sure this doesn't come back. Fixes:66ee620f06("idr: Permit any valid kernel pointer to be stored") Reported-by: Greg Kurz <groug@kaod.org> Signed-off-by: Matthew Wilcox <willy@infradead.org>
80 lines
1.5 KiB
C
80 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.h>
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#include <linux/gfp.h>
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#include <linux/slab.h>
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#include <linux/radix-tree.h>
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#include <linux/rcupdate.h>
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#include <stdlib.h>
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#include <pthread.h>
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#include <stdio.h>
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#include <assert.h>
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#include "regression.h"
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static pthread_barrier_t worker_barrier;
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static int obj0, obj1;
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static RADIX_TREE(mt_tree, GFP_KERNEL);
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static void *reader_fn(void *arg)
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{
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int i;
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void *entry;
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rcu_register_thread();
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pthread_barrier_wait(&worker_barrier);
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for (i = 0; i < 1000000; i++) {
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rcu_read_lock();
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entry = radix_tree_lookup(&mt_tree, 0);
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rcu_read_unlock();
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if (entry != &obj0) {
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printf("iteration %d bad entry = %p\n", i, entry);
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abort();
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}
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}
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rcu_unregister_thread();
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return NULL;
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}
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static void *writer_fn(void *arg)
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{
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int i;
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rcu_register_thread();
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pthread_barrier_wait(&worker_barrier);
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for (i = 0; i < 1000000; i++) {
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radix_tree_insert(&mt_tree, 1, &obj1);
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radix_tree_delete(&mt_tree, 1);
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}
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rcu_unregister_thread();
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return NULL;
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}
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void regression4_test(void)
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{
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pthread_t reader, writer;
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printv(1, "regression test 4 starting\n");
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radix_tree_insert(&mt_tree, 0, &obj0);
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pthread_barrier_init(&worker_barrier, NULL, 2);
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if (pthread_create(&reader, NULL, reader_fn, NULL) ||
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pthread_create(&writer, NULL, writer_fn, NULL)) {
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perror("pthread_create");
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exit(1);
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}
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if (pthread_join(reader, NULL) || pthread_join(writer, NULL)) {
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perror("pthread_join");
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exit(1);
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}
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printv(1, "regression test 4 passed\n");
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}
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