[f2fs-dev] [PATCH v2] f2fs_io: adapt w/ page_size in aligned_xalloc()

[Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

When allocating memory in aligned_xalloc(), if the requested alignment
(e.g., F2FS_DEFAULT_BLKSIZE) is smaller than the system's page size,
aligned_alloc() will allocate memory that is not page-aligned on systems
with 16KB or 64KB page sizes.

As a result, subsequent calls to madvise(..., MADV_HUGEPAGE) will fail
because madvise() requires the memory address and length to be page-aligned.

Fix this by dynamically adjusting the alignment and rounding up the requested
allocation size (via roundup()) to the system's page size, ensuring that
memory is correctly page-aligned for madvise().

Signed-off-by: Chao Yu <chao@kernel.org>
---
 tools/f2fs_io/f2fs_io.c | 17 +++++++++++++++++
 tools/f2fs_io/f2fs_io.h |  3 +++
 2 files changed, 20 insertions(+)

diff --git a/tools/f2fs_io/f2fs_io.c b/tools/f2fs_io/f2fs_io.c
index 94e61b8..9a866cc 100644
--- a/tools/f2fs_io/f2fs_io.c
+++ b/tools/f2fs_io/f2fs_io.c
@@ -97,6 +97,23 @@ static void *xmalloc(size_t size)
 
 static void *aligned_xalloc(size_t alignment, size_t size)
 {
+	long page_size = F2FS_DEFAULT_BLKSIZE;
+
+#ifdef _SC_PAGESIZE
+	page_size = sysconf(_SC_PAGESIZE);
+	if (page_size < 0)
+		page_size = F2FS_DEFAULT_BLKSIZE;
+#endif
+
+	/*
+	 * On systems with large page sizes (e.g., 16KB/64KB), alignment and
+	 * allocation size must be page-aligned to satisfy madvise().
+	 */
+	if (alignment < (size_t)page_size)
+		alignment = page_size;
+
+	size = roundup(size, alignment);
+
 	void *p = aligned_alloc(alignment, size);
 
 	if (!p)
diff --git a/tools/f2fs_io/f2fs_io.h b/tools/f2fs_io/f2fs_io.h
index 539964f..cf1c334 100644
--- a/tools/f2fs_io/f2fs_io.h
+++ b/tools/f2fs_io/f2fs_io.h
@@ -49,6 +49,9 @@ typedef u32	__be32;
 #endif
 
 #define F2FS_DEFAULT_BLKSIZE	4096
+#ifndef roundup
+#define roundup(x, y)		((((x) + ((y) - 1)) / (y)) * (y))
+#endif
 #define NEW_ADDR	0xFFFFFFFF
 
 #ifndef FS_IOC_GETFLAGS
-- 
2.49.0



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