From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- tools/testing/radix-tree/regression3.c | 95 ++++++++++++++++++++++++++++++++++ 1 file changed, 95 insertions(+) create mode 100644 tools/testing/radix-tree/regression3.c (limited to 'tools/testing/radix-tree/regression3.c') diff --git a/tools/testing/radix-tree/regression3.c b/tools/testing/radix-tree/regression3.c new file mode 100644 index 000000000..9f9a3b280 --- /dev/null +++ b/tools/testing/radix-tree/regression3.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Regression3 + * Description: + * Helper radix_tree_iter_retry resets next_index to the current index. + * In following radix_tree_next_slot current chunk size becomes zero. + * This isn't checked and it tries to dereference null pointer in slot. + * + * Helper radix_tree_iter_resume reset slot to NULL and next_index to index + 1, + * for tagger iteraction it also must reset cached tags in iterator to abort + * next radix_tree_next_slot and go to slow-path into radix_tree_next_chunk. + * + * Running: + * This test should run to completion immediately. The above bug would + * cause it to segfault. + * + * Upstream commit: + * Not yet + */ +#include +#include +#include +#include +#include +#include + +#include "regression.h" + +void regression3_test(void) +{ + RADIX_TREE(root, GFP_KERNEL); + void *ptr0 = (void *)4ul; + void *ptr = (void *)8ul; + struct radix_tree_iter iter; + void **slot; + bool first; + + printv(1, "running regression test 3 (should take milliseconds)\n"); + + radix_tree_insert(&root, 0, ptr0); + radix_tree_tag_set(&root, 0, 0); + + first = true; + radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) { + printv(2, "tagged %ld %p\n", iter.index, *slot); + if (first) { + radix_tree_insert(&root, 1, ptr); + radix_tree_tag_set(&root, 1, 0); + first = false; + } + if (radix_tree_deref_retry(*slot)) { + printv(2, "retry at %ld\n", iter.index); + slot = radix_tree_iter_retry(&iter); + continue; + } + } + radix_tree_delete(&root, 1); + + first = true; + radix_tree_for_each_slot(slot, &root, &iter, 0) { + printv(2, "slot %ld %p\n", iter.index, *slot); + if (first) { + radix_tree_insert(&root, 1, ptr); + first = false; + } + if (radix_tree_deref_retry(*slot)) { + printv(2, "retry at %ld\n", iter.index); + slot = radix_tree_iter_retry(&iter); + continue; + } + } + + radix_tree_for_each_slot(slot, &root, &iter, 0) { + printv(2, "slot %ld %p\n", iter.index, *slot); + if (!iter.index) { + printv(2, "next at %ld\n", iter.index); + slot = radix_tree_iter_resume(slot, &iter); + } + } + + radix_tree_tag_set(&root, 0, 0); + radix_tree_tag_set(&root, 1, 0); + radix_tree_for_each_tagged(slot, &root, &iter, 0, 0) { + printv(2, "tagged %ld %p\n", iter.index, *slot); + if (!iter.index) { + printv(2, "next at %ld\n", iter.index); + slot = radix_tree_iter_resume(slot, &iter); + } + } + + radix_tree_delete(&root, 0); + radix_tree_delete(&root, 1); + + printv(1, "regression test 3 passed\n"); +} -- cgit v1.3.1