selftests/bpf: Add a test for objects stuck in free_by_rcu_ttracegrafted

Delete all elements of BPF_F_NO_PREALLOC hash map in one batch. The first
free_bulk() starts RCU tasks trace GP and the rest of the elements are
freed while it's in flight. Wait for call_rcu_ttrace_in_progress to clear
in bpf_mem_cache of every cpu and check that free_by_rcu_ttrace and
waiting_for_gp_ttrace lists are empty.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20260930095920.601738-4-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 246 insertions, 0 deletions

diff --git a/fs/hfsplus/bitmap.c b/fs/hfsplus/bitmap.c
new file mode 100644
index 000000000..1b3af8c87
--- /dev/null
+++ b/fs/hfsplus/bitmap.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/fs/hfsplus/bitmap.c
+ *
+ * Copyright (C) 2001
+ * Brad Boyer (flar@allandria.com)
+ * (C) 2003 Ardis Technologies <roman@ardistech.com>
+ *
+ * Handling of allocation file
+ */
+
+#include <linux/pagemap.h>
+
+#include "hfsplus_fs.h"
+#include "hfsplus_raw.h"
+
+#define PAGE_CACHE_BITS	(PAGE_SIZE * 8)
+
+int hfsplus_block_allocate(struct super_block *sb, u32 size,
+		u32 offset, u32 *max)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+	struct page *page;
+	struct address_space *mapping;
+	__be32 *pptr, *curr, *end;
+	u32 mask, start, len, n;
+	__be32 val;
+	int i;
+
+	len = *max;
+	if (!len)
+		return size;
+
+	hfs_dbg("size %u, offset %u, len %u\n", size, offset, len);
+	mutex_lock(&sbi->alloc_mutex);
+	mapping = sbi->alloc_file->i_mapping;
+	page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS, NULL);
+	if (IS_ERR(page)) {
+		start = size;
+		goto out;
+	}
+	pptr = kmap_local_page(page);
+	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
+	i = offset % 32;
+	offset &= ~(PAGE_CACHE_BITS - 1);
+	if ((size ^ offset) / PAGE_CACHE_BITS)
+		end = pptr + PAGE_CACHE_BITS / 32;
+	else
+		end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
+
+	/* scan the first partial u32 for zero bits */
+	val = *curr;
+	if (~val) {
+		n = be32_to_cpu(val);
+		mask = (1U << 31) >> i;
+		for (; i < 32; mask >>= 1, i++) {
+			if (!(n & mask))
+				goto found;
+		}
+	}
+	curr++;
+
+	/* scan complete u32s for the first zero bit */
+	while (1) {
+		while (curr < end) {
+			val = *curr;
+			if (~val) {
+				n = be32_to_cpu(val);
+				mask = 1 << 31;
+				for (i = 0; i < 32; mask >>= 1, i++) {
+					if (!(n & mask))
+						goto found;
+				}
+			}
+			curr++;
+		}
+		kunmap_local(pptr);
+		offset += PAGE_CACHE_BITS;
+		if (offset >= size)
+			break;
+		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
+					 NULL);
+		if (IS_ERR(page)) {
+			start = size;
+			goto out;
+		}
+		curr = pptr = kmap_local_page(page);
+		if ((size ^ offset) / PAGE_CACHE_BITS)
+			end = pptr + PAGE_CACHE_BITS / 32;
+		else
+			end = pptr + ((size + 31) & (PAGE_CACHE_BITS - 1)) / 32;
+	}
+	hfs_dbg("bitmap full\n");
+	start = size;
+	goto out;
+
+found:
+	start = offset + (curr - pptr) * 32 + i;
+	if (start >= size) {
+		hfs_dbg("bitmap full\n");
+		goto out;
+	}
+	/* do any partial u32 at the start */
+	len = min(size - start, len);
+	while (1) {
+		n |= mask;
+		if (++i >= 32)
+			break;
+		mask >>= 1;
+		if (!--len || n & mask)
+			goto done;
+	}
+	if (!--len)
+		goto done;
+	*curr++ = cpu_to_be32(n);
+	/* do full u32s */
+	while (1) {
+		while (curr < end) {
+			n = be32_to_cpu(*curr);
+			if (len < 32)
+				goto last;
+			if (n) {
+				len = 32;
+				goto last;
+			}
+			*curr++ = cpu_to_be32(0xffffffff);
+			len -= 32;
+		}
+		set_page_dirty(page);
+		kunmap_local(pptr);
+		offset += PAGE_CACHE_BITS;
+		page = read_mapping_page(mapping, offset / PAGE_CACHE_BITS,
+					 NULL);
+		if (IS_ERR(page)) {
+			start = size;
+			goto out;
+		}
+		pptr = kmap_local_page(page);
+		curr = pptr;
+		end = pptr + PAGE_CACHE_BITS / 32;
+	}
+last:
+	/* do any partial u32 at end */
+	mask = 1U << 31;
+	for (i = 0; i < len; i++) {
+		if (n & mask)
+			break;
+		n |= mask;
+		mask >>= 1;
+	}
+done:
+	*curr = cpu_to_be32(n);
+	set_page_dirty(page);
+	kunmap_local(pptr);
+	*max = offset + (curr - pptr) * 32 + i - start;
+	sbi->free_blocks -= *max;
+	hfsplus_mark_mdb_dirty(sb);
+	hfs_dbg("start %u, max %u\n", start, *max);
+out:
+	mutex_unlock(&sbi->alloc_mutex);
+	return start;
+}
+
+int hfsplus_block_free(struct super_block *sb, u32 offset, u32 count)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+	struct page *page;
+	struct address_space *mapping;
+	__be32 *pptr, *curr, *end;
+	u32 mask, len, pnr;
+	int i;
+
+	/* is there any actual work to be done? */
+	if (!count)
+		return 0;
+
+	hfs_dbg("offset %u, count %u\n", offset, count);
+	/* are all of the bits in range? */
+	if ((offset + count) > sbi->total_blocks)
+		return -ENOENT;
+
+	mutex_lock(&sbi->alloc_mutex);
+	mapping = sbi->alloc_file->i_mapping;
+	pnr = offset / PAGE_CACHE_BITS;
+	page = read_mapping_page(mapping, pnr, NULL);
+	if (IS_ERR(page))
+		goto kaboom;
+	pptr = kmap_local_page(page);
+	curr = pptr + (offset & (PAGE_CACHE_BITS - 1)) / 32;
+	end = pptr + PAGE_CACHE_BITS / 32;
+	len = count;
+
+	/* do any partial u32 at the start */
+	i = offset % 32;
+	if (i) {
+		int j = 32 - i;
+		mask = 0xffffffffU << j;
+		if (j > count) {
+			mask |= 0xffffffffU >> (i + count);
+			*curr++ &= cpu_to_be32(mask);
+			goto out;
+		}
+		*curr++ &= cpu_to_be32(mask);
+		count -= j;
+	}
+
+	/* do full u32s */
+	while (1) {
+		while (curr < end) {
+			if (count < 32)
+				goto done;
+			*curr++ = 0;
+			count -= 32;
+		}
+		if (!count)
+			break;
+		set_page_dirty(page);
+		kunmap_local(pptr);
+		page = read_mapping_page(mapping, ++pnr, NULL);
+		if (IS_ERR(page))
+			goto kaboom;
+		pptr = kmap_local_page(page);
+		curr = pptr;
+		end = pptr + PAGE_CACHE_BITS / 32;
+	}
+done:
+	/* do any partial u32 at end */
+	if (count) {
+		mask = 0xffffffffU >> count;
+		*curr &= cpu_to_be32(mask);
+	}
+out:
+	set_page_dirty(page);
+	kunmap_local(pptr);
+	sbi->free_blocks += len;
+	hfsplus_mark_mdb_dirty(sb);
+	mutex_unlock(&sbi->alloc_mutex);
+
+	return 0;
+
+kaboom:
+	pr_crit("unable to mark blocks free: error %ld\n", PTR_ERR(page));
+	mutex_unlock(&sbi->alloc_mutex);
+
+	return -EIO;
+}