Patch "md: free unused memory after bitmap resize" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

md: free unused memory after bitmap resize

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
md-free-unused-memory-after-bitmap-resize.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Zdenek Kabelac <[email protected]>
Date: Wed, 8 Nov 2017 13:44:56 +0100
Subject: md: free unused memory after bitmap resize

From: Zdenek Kabelac <[email protected]>

[ Upstream commit 0868b99c214a3d55486c700de7c3f770b7243e7c ]

When bitmap is resized, the old kalloced chunks just are not released once the resized bitmap starts to use new space.

This fixes in particular kmemleak reports like this one:

unreferenced object 0xffff8f4311e9c000 (size 4096):
comm "lvm", pid 19333, jiffies 4295263268 (age 528.265s) hex dump (first 32 bytes):

    02 80 02 80 02 80 02 80 02 80 02 80 02 80 02 80  ................
    02 80 02 80 02 80 02 80 02 80 02 80 02 80 02 80  ................
  backtrace:
    [<ffffffffa69471ca>] kmemleak_alloc+0x4a/0xa0
    [<ffffffffa628c10e>] kmem_cache_alloc_trace+0x14e/0x2e0
    [<ffffffffa676cfec>] bitmap_checkpage+0x7c/0x110
    [<ffffffffa676d0c5>] bitmap_get_counter+0x45/0xd0
    [<ffffffffa676d6b3>] bitmap_set_memory_bits+0x43/0xe0
    [<ffffffffa676e41c>] bitmap_init_from_disk+0x23c/0x530
    [<ffffffffa676f1ae>] bitmap_load+0xbe/0x160
    [<ffffffffc04c47d3>] raid_preresume+0x203/0x2f0 [dm_raid]
    [<ffffffffa677762f>] dm_table_resume_targets+0x4f/0xe0
    [<ffffffffa6774b52>] dm_resume+0x122/0x140
    [<ffffffffa6779b9f>] dev_suspend+0x18f/0x290
    [<ffffffffa677a3a7>] ctl_ioctl+0x287/0x560
    [<ffffffffa677a693>] dm_ctl_ioctl+0x13/0x20
    [<ffffffffa62d6b46>] do_vfs_ioctl+0xa6/0x750
    [<ffffffffa62d7269>] SyS_ioctl+0x79/0x90
    [<ffffffffa6956d41>] entry_SYSCALL_64_fastpath+0x1f/0xc2

---
 drivers/md/bitmap.c |    9 +++++++++
 1 file changed, 9 insertions(+)

@@ -2084,6 +2084,7 @@ int bitmap_resize(struct bitmap *bitmap,
 				for (k = 0; k < page; k++) {
 					kfree(new_bp[k].map);
 				}
+				kfree(new_bp);
 
 				/* restore some fields from old_counts */
 				bitmap->counts.bp = old_counts.bp;

@@ -2134,6 +2135,14 @@ int bitmap_resize(struct bitmap *bitmap,
 		block += old_blocks;
 	}
 
+	if (bitmap->counts.bp != old_counts.bp) {
+		unsigned long k;
+		for (k = 0; k < old_counts.pages; k++)
+			if (!old_counts.bp[k].hijacked)
+				kfree(old_counts.bp[k].map);
+		kfree(old_counts.bp);
+	}
+
 	if (!init) {
 		int i;
 		while (block < (chunks << chunkshift)) {

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/md-free-unused-memory-after-bitmap-resize.patch