The patch titled
Subject: mm/mremap: fix WARN with uffd that has remap events disabled
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-mremap-fix-warn-with-uffd-that-has-remap-events-disabled.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: David Hildenbrand <david(a)redhat.com>
Subject: mm/mremap: fix WARN with uffd that has remap events disabled
Date: Mon, 18 Aug 2025 19:53:58 +0200
Registering userfaultd on a VMA that spans at least one PMD and then
mremap()'ing that VMA can trigger a WARN when recovering from a failed
page table move due to a page table allocation error.
The code ends up doing the right thing (recurse, avoiding moving actual
page tables), but triggering that WARN is unpleasant:
WARNING: CPU: 2 PID: 6133 at mm/mremap.c:357 move_normal_pmd mm/mremap.c:357 [inline]
WARNING: CPU: 2 PID: 6133 at mm/mremap.c:357 move_pgt_entry mm/mremap.c:595 [inline]
WARNING: CPU: 2 PID: 6133 at mm/mremap.c:357 move_page_tables+0x3832/0x44a0 mm/mremap.c:852
Modules linked in:
CPU: 2 UID: 0 PID: 6133 Comm: syz.0.19 Not tainted 6.17.0-rc1-syzkaller-00004-g53e760d89498 #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:move_normal_pmd mm/mremap.c:357 [inline]
RIP: 0010:move_pgt_entry mm/mremap.c:595 [inline]
RIP: 0010:move_page_tables+0x3832/0x44a0 mm/mremap.c:852
Code: ...
RSP: 0018:ffffc900037a76d8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: 0000000032930007 RCX: ffffffff820c6645
RDX: ffff88802e56a440 RSI: ffffffff820c7201 RDI: 0000000000000007
RBP: ffff888037728fc0 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000032930007 R11: 0000000000000000 R12: 0000000000000000
R13: ffffc900037a79a8 R14: 0000000000000001 R15: dffffc0000000000
FS: 000055556316a500(0000) GS:ffff8880d68bc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30863fff CR3: 0000000050171000 CR4: 0000000000352ef0
Call Trace:
<TASK>
copy_vma_and_data+0x468/0x790 mm/mremap.c:1215
move_vma+0x548/0x1780 mm/mremap.c:1282
mremap_to+0x1b7/0x450 mm/mremap.c:1406
do_mremap+0xfad/0x1f80 mm/mremap.c:1921
__do_sys_mremap+0x119/0x170 mm/mremap.c:1977
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f00d0b8ebe9
Code: ...
RSP: 002b:00007ffe5ea5ee98 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
RAX: ffffffffffffffda RBX: 00007f00d0db5fa0 RCX: 00007f00d0b8ebe9
RDX: 0000000000400000 RSI: 0000000000c00000 RDI: 0000200000000000
RBP: 00007ffe5ea5eef0 R08: 0000200000c00000 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000002
R13: 00007f00d0db5fa0 R14: 00007f00d0db5fa0 R15: 0000000000000005
</TASK>
The underlying issue is that we recurse during the original page table
move, but not during the recovery move.
Fix it by checking for both VMAs and performing the check before the
pmd_none() sanity check.
Add a new helper where we perform+document that check for the PMD and PUD
level.
Thanks to Harry for bisecting.
Link: https://lkml.kernel.org/r/20250818175358.1184757-1-david@redhat.com
Fixes: 0cef0bb836e ("mm: clear uffd-wp PTE/PMD state on mremap()")
Signed-off-by: David Hildenbrand <david(a)redhat.com>
Reported-by: syzbot+4d9a13f0797c46a29e42(a)syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/689bb893.050a0220.7f033.013a.GAE@google.com
Cc: "Liam R. Howlett" <Liam.Howlett(a)oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: Jann Horn <jannh(a)google.com>
Cc: Pedro Falcato <pfalcato(a)suse.de>
Cc: Harry Yoo <harry.yoo(a)oracle.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/mremap.c | 41 +++++++++++++++++++++++------------------
1 file changed, 23 insertions(+), 18 deletions(-)
--- a/mm/mremap.c~mm-mremap-fix-warn-with-uffd-that-has-remap-events-disabled
+++ a/mm/mremap.c
@@ -323,6 +323,25 @@ static inline bool arch_supports_page_ta
}
#endif
+static inline bool uffd_supports_page_table_move(struct pagetable_move_control *pmc)
+{
+ /*
+ * If we are moving a VMA that has uffd-wp registered but with
+ * remap events disabled (new VMA will not be registered with uffd), we
+ * need to ensure that the uffd-wp state is cleared from all pgtables.
+ * This means recursing into lower page tables in move_page_tables().
+ *
+ * We might get called with VMAs reversed when recovering from a
+ * failed page table move. In that case, the
+ * "old"-but-actually-"originally new" VMA during recovery will not have
+ * a uffd context. Recursing into lower page tables during the original
+ * move but not during the recovery move will cause trouble, because we
+ * run into already-existing page tables. So check both VMAs.
+ */
+ return !vma_has_uffd_without_event_remap(pmc->old) &&
+ !vma_has_uffd_without_event_remap(pmc->new);
+}
+
#ifdef CONFIG_HAVE_MOVE_PMD
static bool move_normal_pmd(struct pagetable_move_control *pmc,
pmd_t *old_pmd, pmd_t *new_pmd)
@@ -335,6 +354,8 @@ static bool move_normal_pmd(struct paget
if (!arch_supports_page_table_move())
return false;
+ if (!uffd_supports_page_table_move(pmc))
+ return false;
/*
* The destination pmd shouldn't be established, free_pgtables()
* should have released it.
@@ -361,15 +382,6 @@ static bool move_normal_pmd(struct paget
if (WARN_ON_ONCE(!pmd_none(*new_pmd)))
return false;
- /* If this pmd belongs to a uffd vma with remap events disabled, we need
- * to ensure that the uffd-wp state is cleared from all pgtables. This
- * means recursing into lower page tables in move_page_tables(), and we
- * can reuse the existing code if we simply treat the entry as "not
- * moved".
- */
- if (vma_has_uffd_without_event_remap(vma))
- return false;
-
/*
* We don't have to worry about the ordering of src and dst
* ptlocks because exclusive mmap_lock prevents deadlock.
@@ -418,6 +430,8 @@ static bool move_normal_pud(struct paget
if (!arch_supports_page_table_move())
return false;
+ if (!uffd_supports_page_table_move(pmc))
+ return false;
/*
* The destination pud shouldn't be established, free_pgtables()
* should have released it.
@@ -425,15 +439,6 @@ static bool move_normal_pud(struct paget
if (WARN_ON_ONCE(!pud_none(*new_pud)))
return false;
- /* If this pud belongs to a uffd vma with remap events disabled, we need
- * to ensure that the uffd-wp state is cleared from all pgtables. This
- * means recursing into lower page tables in move_page_tables(), and we
- * can reuse the existing code if we simply treat the entry as "not
- * moved".
- */
- if (vma_has_uffd_without_event_remap(vma))
- return false;
-
/*
* We don't have to worry about the ordering of src and dst
* ptlocks because exclusive mmap_lock prevents deadlock.
_
Patches currently in -mm which might be from david(a)redhat.com are
mm-mremap-fix-warn-with-uffd-that-has-remap-events-disabled.patch
mm-migrate-remove-migratepage_unmap.patch
treewide-remove-migratepage_success.patch
mm-huge_memory-move-more-common-code-into-insert_pmd.patch
mm-huge_memory-move-more-common-code-into-insert_pud.patch
mm-huge_memory-support-huge-zero-folio-in-vmf_insert_folio_pmd.patch
fs-dax-use-vmf_insert_folio_pmd-to-insert-the-huge-zero-folio.patch
mm-huge_memory-mark-pmd-mappings-of-the-huge-zero-folio-special.patch
powerpc-ptdump-rename-struct-pgtable_level-to-struct-ptdump_pglevel.patch
mm-rmap-convert-enum-rmap_level-to-enum-pgtable_level.patch
mm-memory-convert-print_bad_pte-to-print_bad_page_map.patch
mm-memory-factor-out-common-code-from-vm_normal_page_.patch
mm-introduce-and-use-vm_normal_page_pud.patch
mm-rename-vm_ops-find_special_page-to-vm_ops-find_normal_page.patch
prctl-extend-pr_set_thp_disable-to-optionally-exclude-vm_hugepage.patch
mm-huge_memory-convert-tva_flags-to-enum-tva_type.patch
mm-huge_memory-respect-madv_collapse-with-pr_thp_disable_except_advised.patch
The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x d2845519b0723c5d5a0266cbf410495f9b8fd65c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081858-issuing-conclude-4ff3@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d2845519b0723c5d5a0266cbf410495f9b8fd65c Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch(a)lst.de>
Date: Wed, 23 Jul 2025 14:19:44 +0200
Subject: [PATCH] xfs: fully decouple XFS_IBULK* flags from XFS_IWALK* flags
Fix up xfs_inumbers to now pass in the XFS_IBULK* flags into the flags
argument to xfs_inobt_walk, which expects the XFS_IWALK* flags.
Currently passing the wrong flags works for non-debug builds because
the only XFS_IWALK* flag has the same encoding as the corresponding
XFS_IBULK* flag, but in debug builds it can trigger an assert that no
incorrect flag is passed. Instead just extra the relevant flag.
Fixes: 5b35d922c52798 ("xfs: Decouple XFS_IBULK flags from XFS_IWALK flags")
Cc: <stable(a)vger.kernel.org> # v5.19
Reported-by: cen zhang <zzzccc427(a)gmail.com>
Signed-off-by: Christoph Hellwig <hch(a)lst.de>
Reviewed-by: Darrick J. Wong <djwong(a)kernel.org>
Signed-off-by: Carlos Maiolino <cem(a)kernel.org>
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index c8c9b8d8309f..5116842420b2 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -447,17 +447,21 @@ xfs_inumbers(
.breq = breq,
};
struct xfs_trans *tp;
+ unsigned int iwalk_flags = 0;
int error = 0;
if (xfs_bulkstat_already_done(breq->mp, breq->startino))
return 0;
+ if (breq->flags & XFS_IBULK_SAME_AG)
+ iwalk_flags |= XFS_IWALK_SAME_AG;
+
/*
* Grab an empty transaction so that we can use its recursive buffer
* locking abilities to detect cycles in the inobt without deadlocking.
*/
tp = xfs_trans_alloc_empty(breq->mp);
- error = xfs_inobt_walk(breq->mp, tp, breq->startino, breq->flags,
+ error = xfs_inobt_walk(breq->mp, tp, breq->startino, iwalk_flags,
xfs_inumbers_walk, breq->icount, &ic);
xfs_trans_cancel(tp);
The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 005b0a0c24e1628313e951516b675109a92cacfe
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081840-stomp-enhance-b456@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 005b0a0c24e1628313e951516b675109a92cacfe Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana(a)suse.com>
Date: Fri, 18 Jul 2025 13:07:29 +0100
Subject: [PATCH] btrfs: send: use fallocate for hole punching with send stream
v2
Currently holes are sent as writes full of zeroes, which results in
unnecessarily using disk space at the receiving end and increasing the
stream size.
In some cases we avoid sending writes of zeroes, like during a full
send operation where we just skip writes for holes.
But for some cases we fill previous holes with writes of zeroes too, like
in this scenario:
1) We have a file with a hole in the range [2M, 3M), we snapshot the
subvolume and do a full send. The range [2M, 3M) stays as a hole at
the receiver since we skip sending write commands full of zeroes;
2) We punch a hole for the range [3M, 4M) in our file, so that now it
has a 2M hole in the range [2M, 4M), and snapshot the subvolume.
Now if we do an incremental send, we will send write commands full
of zeroes for the range [2M, 4M), removing the hole for [2M, 3M) at
the receiver.
We could improve cases such as this last one by doing additional
comparisons of file extent items (or their absence) between the parent
and send snapshots, but that's a lot of code to add plus additional CPU
and IO costs.
Since the send stream v2 already has a fallocate command and btrfs-progs
implements a callback to execute fallocate since the send stream v2
support was added to it, update the kernel to use fallocate for punching
holes for V2+ streams.
Test coverage is provided by btrfs/284 which is a version of btrfs/007
that exercises send stream v2 instead of v1, using fsstress with random
operations and fssum to verify file contents.
Link: https://github.com/kdave/btrfs-progs/issues/1001
CC: stable(a)vger.kernel.org # 6.1+
Reviewed-by: Boris Burkov <boris(a)bur.io>
Signed-off-by: Filipe Manana <fdmanana(a)suse.com>
Reviewed-by: David Sterba <dsterba(a)suse.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index 09822e766e41..7664025a5af4 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -4,6 +4,7 @@
*/
#include <linux/bsearch.h>
+#include <linux/falloc.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/sort.h>
@@ -5405,6 +5406,30 @@ static int send_update_extent(struct send_ctx *sctx,
return ret;
}
+static int send_fallocate(struct send_ctx *sctx, u32 mode, u64 offset, u64 len)
+{
+ struct fs_path *path;
+ int ret;
+
+ path = get_cur_inode_path(sctx);
+ if (IS_ERR(path))
+ return PTR_ERR(path);
+
+ ret = begin_cmd(sctx, BTRFS_SEND_C_FALLOCATE);
+ if (ret < 0)
+ return ret;
+
+ TLV_PUT_PATH(sctx, BTRFS_SEND_A_PATH, path);
+ TLV_PUT_U32(sctx, BTRFS_SEND_A_FALLOCATE_MODE, mode);
+ TLV_PUT_U64(sctx, BTRFS_SEND_A_FILE_OFFSET, offset);
+ TLV_PUT_U64(sctx, BTRFS_SEND_A_SIZE, len);
+
+ ret = send_cmd(sctx);
+
+tlv_put_failure:
+ return ret;
+}
+
static int send_hole(struct send_ctx *sctx, u64 end)
{
struct fs_path *p = NULL;
@@ -5412,6 +5437,14 @@ static int send_hole(struct send_ctx *sctx, u64 end)
u64 offset = sctx->cur_inode_last_extent;
int ret = 0;
+ /*
+ * Starting with send stream v2 we have fallocate and can use it to
+ * punch holes instead of sending writes full of zeroes.
+ */
+ if (proto_cmd_ok(sctx, BTRFS_SEND_C_FALLOCATE))
+ return send_fallocate(sctx, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
+ offset, end - offset);
+
/*
* A hole that starts at EOF or beyond it. Since we do not yet support
* fallocate (for extent preallocation and hole punching), sending a
From: Su Hui <suhui(a)nfschina.com>
[ Upstream commit 7919407eca2ef562fa6c98c41cfdf6f6cdd69d92 ]
When encounters some errors like these:
xhci_hcd 0000:4a:00.2: xHCI dying or halted, can't queue_command
xhci_hcd 0000:4a:00.2: FIXME: allocate a command ring segment
usb usb5-port6: couldn't allocate usb_device
It's hard to know whether xhc_state is dying or halted. So it's better
to print xhc_state's value which can help locate the resaon of the bug.
Signed-off-by: Su Hui <suhui(a)nfschina.com>
Link: https://lore.kernel.org/r/20250725060117.1773770-1-suhui@nfschina.com
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
LLM Generated explanations, may be completely bogus:
**Backport Status: YES**
This commit is suitable for backporting to stable kernel trees for the
following reasons:
1. **Enhanced Debugging for Real-World Issues**: The commit improves
debugging of USB xHCI host controller failures by printing the actual
`xhc_state` value when `queue_command` fails. The commit message
shows real error messages users encounter ("xHCI dying or halted,
can't queue_command"), demonstrating this is a real-world debugging
problem.
2. **Minimal and Safe Change**: The change is extremely small and safe -
it only modifies a debug print statement from:
```c
xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n");
```
to:
```c
xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state:
0x%x\n", xhci->xhc_state);
```
3. **No Functional Changes**: This is a pure diagnostic improvement. It
doesn't change any logic, control flow, or data structures. It only
adds the state value (0x%x format) to an existing debug message.
4. **Important for Troubleshooting**: The xHCI driver is critical for
USB functionality, and when it fails with "dying or halted" states,
knowing the exact state helps diagnose whether:
- `XHCI_STATE_DYING` (0x1) - controller is dying
- `XHCI_STATE_HALTED` (0x2) - controller is halted
- Both states (0x3) - controller has both flags set
This distinction is valuable for debugging hardware issues, driver
bugs, or system problems.
5. **Zero Risk of Regression**: Adding a parameter to a debug print
statement has no risk of introducing regressions. The worst case is
the debug message prints the state value.
6. **Follows Stable Rules**: This meets stable kernel criteria as it:
- Fixes a real debugging limitation
- Is obviously correct
- Has been tested (signed-off and accepted by Greg KH)
- Is small (single line change)
- Doesn't add new features, just improves existing diagnostics
The commit helps system administrators and developers diagnose USB
issues more effectively by providing the actual state value rather than
just saying "dying or halted", making it a valuable debugging
enhancement for stable kernels.
drivers/usb/host/xhci-ring.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 2ff8787f753c..19978f02bb9e 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -4378,7 +4378,8 @@ static int queue_command(struct xhci_hcd *xhci, struct xhci_command *cmd,
if ((xhci->xhc_state & XHCI_STATE_DYING) ||
(xhci->xhc_state & XHCI_STATE_HALTED)) {
- xhci_dbg(xhci, "xHCI dying or halted, can't queue_command\n");
+ xhci_dbg(xhci, "xHCI dying or halted, can't queue_command. state: 0x%x\n",
+ xhci->xhc_state);
return -ESHUTDOWN;
}
--
2.39.5
The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 62be7afcc13b2727bdc6a4c91aefed6b452e6ecc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081853-parrot-skeleton-78e1@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 62be7afcc13b2727bdc6a4c91aefed6b452e6ecc Mon Sep 17 00:00:00 2001
From: Naohiro Aota <naohiro.aota(a)wdc.com>
Date: Sun, 29 Jun 2025 23:18:29 +0900
Subject: [PATCH] btrfs: zoned: requeue to unused block group list if zone
finish failed
btrfs_zone_finish() can fail for several reason. If it is -EAGAIN, we need
to try it again later. So, put the block group to the retry list properly.
Failing to do so will keep the removable block group intact until remount
and can causes unnecessary ENOSPC.
Fixes: 74e91b12b115 ("btrfs: zoned: zone finish unused block group")
CC: stable(a)vger.kernel.org # 6.1+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn(a)wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota(a)wdc.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 3ddf9fe52b9d..47c6d040176c 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1639,8 +1639,10 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
ret = btrfs_zone_finish(block_group);
if (ret < 0) {
btrfs_dec_block_group_ro(block_group);
- if (ret == -EAGAIN)
+ if (ret == -EAGAIN) {
+ btrfs_link_bg_list(block_group, &retry_list);
ret = 0;
+ }
goto next;
}
The patch below does not apply to the 6.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.15.y
git checkout FETCH_HEAD
git cherry-pick -x d2845519b0723c5d5a0266cbf410495f9b8fd65c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081857-glitter-hummus-4836@gregkh' --subject-prefix 'PATCH 6.15.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d2845519b0723c5d5a0266cbf410495f9b8fd65c Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch(a)lst.de>
Date: Wed, 23 Jul 2025 14:19:44 +0200
Subject: [PATCH] xfs: fully decouple XFS_IBULK* flags from XFS_IWALK* flags
Fix up xfs_inumbers to now pass in the XFS_IBULK* flags into the flags
argument to xfs_inobt_walk, which expects the XFS_IWALK* flags.
Currently passing the wrong flags works for non-debug builds because
the only XFS_IWALK* flag has the same encoding as the corresponding
XFS_IBULK* flag, but in debug builds it can trigger an assert that no
incorrect flag is passed. Instead just extra the relevant flag.
Fixes: 5b35d922c52798 ("xfs: Decouple XFS_IBULK flags from XFS_IWALK flags")
Cc: <stable(a)vger.kernel.org> # v5.19
Reported-by: cen zhang <zzzccc427(a)gmail.com>
Signed-off-by: Christoph Hellwig <hch(a)lst.de>
Reviewed-by: Darrick J. Wong <djwong(a)kernel.org>
Signed-off-by: Carlos Maiolino <cem(a)kernel.org>
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index c8c9b8d8309f..5116842420b2 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -447,17 +447,21 @@ xfs_inumbers(
.breq = breq,
};
struct xfs_trans *tp;
+ unsigned int iwalk_flags = 0;
int error = 0;
if (xfs_bulkstat_already_done(breq->mp, breq->startino))
return 0;
+ if (breq->flags & XFS_IBULK_SAME_AG)
+ iwalk_flags |= XFS_IWALK_SAME_AG;
+
/*
* Grab an empty transaction so that we can use its recursive buffer
* locking abilities to detect cycles in the inobt without deadlocking.
*/
tp = xfs_trans_alloc_empty(breq->mp);
- error = xfs_inobt_walk(breq->mp, tp, breq->startino, breq->flags,
+ error = xfs_inobt_walk(breq->mp, tp, breq->startino, iwalk_flags,
xfs_inumbers_walk, breq->icount, &ic);
xfs_trans_cancel(tp);
The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 33e8f24b52d2796b8cfb28c19a1a7dd6476323a8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081821-debating-askew-bf1e@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 33e8f24b52d2796b8cfb28c19a1a7dd6476323a8 Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana(a)suse.com>
Date: Mon, 19 May 2025 11:07:29 +0100
Subject: [PATCH] btrfs: abort transaction on unexpected eb generation at
btrfs_copy_root()
If we find an unexpected generation for the extent buffer we are cloning
at btrfs_copy_root(), we just WARN_ON() and don't error out and abort the
transaction, meaning we allow to persist metadata with an unexpected
generation. Instead of warning only, abort the transaction and return
-EUCLEAN.
CC: stable(a)vger.kernel.org # 6.1+
Reviewed-by: Daniel Vacek <neelx(a)suse.com>
Reviewed-by: Qu Wenruo <wqu(a)suse.com>
Signed-off-by: Filipe Manana <fdmanana(a)suse.com>
Reviewed-by: David Sterba <dsterba(a)suse.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ae6cd77282f5..a5ee6ce312cf 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -283,7 +283,14 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
- WARN_ON(btrfs_header_generation(buf) > trans->transid);
+ if (unlikely(btrfs_header_generation(buf) > trans->transid)) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ ret = -EUCLEAN;
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+
if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
ret = btrfs_inc_ref(trans, root, cow, 1);
if (ret)
The patch below does not apply to the 6.16-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.16.y
git checkout FETCH_HEAD
git cherry-pick -x d2845519b0723c5d5a0266cbf410495f9b8fd65c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081857-swerve-preschool-2c2c@gregkh' --subject-prefix 'PATCH 6.16.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From d2845519b0723c5d5a0266cbf410495f9b8fd65c Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch(a)lst.de>
Date: Wed, 23 Jul 2025 14:19:44 +0200
Subject: [PATCH] xfs: fully decouple XFS_IBULK* flags from XFS_IWALK* flags
Fix up xfs_inumbers to now pass in the XFS_IBULK* flags into the flags
argument to xfs_inobt_walk, which expects the XFS_IWALK* flags.
Currently passing the wrong flags works for non-debug builds because
the only XFS_IWALK* flag has the same encoding as the corresponding
XFS_IBULK* flag, but in debug builds it can trigger an assert that no
incorrect flag is passed. Instead just extra the relevant flag.
Fixes: 5b35d922c52798 ("xfs: Decouple XFS_IBULK flags from XFS_IWALK flags")
Cc: <stable(a)vger.kernel.org> # v5.19
Reported-by: cen zhang <zzzccc427(a)gmail.com>
Signed-off-by: Christoph Hellwig <hch(a)lst.de>
Reviewed-by: Darrick J. Wong <djwong(a)kernel.org>
Signed-off-by: Carlos Maiolino <cem(a)kernel.org>
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index c8c9b8d8309f..5116842420b2 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -447,17 +447,21 @@ xfs_inumbers(
.breq = breq,
};
struct xfs_trans *tp;
+ unsigned int iwalk_flags = 0;
int error = 0;
if (xfs_bulkstat_already_done(breq->mp, breq->startino))
return 0;
+ if (breq->flags & XFS_IBULK_SAME_AG)
+ iwalk_flags |= XFS_IWALK_SAME_AG;
+
/*
* Grab an empty transaction so that we can use its recursive buffer
* locking abilities to detect cycles in the inobt without deadlocking.
*/
tp = xfs_trans_alloc_empty(breq->mp);
- error = xfs_inobt_walk(breq->mp, tp, breq->startino, breq->flags,
+ error = xfs_inobt_walk(breq->mp, tp, breq->startino, iwalk_flags,
xfs_inumbers_walk, breq->icount, &ic);
xfs_trans_cancel(tp);
The patch below does not apply to the 6.16-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.16.y
git checkout FETCH_HEAD
git cherry-pick -x ad580dfa388fabb52af033e3f8cc5d04be985e54
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081814-monsoon-supermom-44bb@gregkh' --subject-prefix 'PATCH 6.16.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From ad580dfa388fabb52af033e3f8cc5d04be985e54 Mon Sep 17 00:00:00 2001
From: Leo Martins <loemra.dev(a)gmail.com>
Date: Mon, 21 Jul 2025 10:49:16 -0700
Subject: [PATCH] btrfs: fix subpage deadlock in
try_release_subpage_extent_buffer()
There is a potential deadlock that can happen in
try_release_subpage_extent_buffer() because the irq-safe xarray spin
lock fs_info->buffer_tree is being acquired before the irq-unsafe
eb->refs_lock.
This leads to the potential race:
// T1 (random eb->refs user) // T2 (release folio)
spin_lock(&eb->refs_lock);
// interrupt
end_bbio_meta_write()
btrfs_meta_folio_clear_writeback()
btree_release_folio()
folio_test_writeback() //false
try_release_extent_buffer()
try_release_subpage_extent_buffer()
xa_lock_irq(&fs_info->buffer_tree)
spin_lock(&eb->refs_lock); // blocked; held by T1
buffer_tree_clear_mark()
xas_lock_irqsave() // blocked; held by T2
I believe that the spin lock can safely be replaced by an rcu_read_lock.
The xa_for_each loop does not need the spin lock as it's already
internally protected by the rcu_read_lock. The extent buffer is also
protected by the rcu_read_lock so it won't be freed before we take the
eb->refs_lock and check the ref count.
The rcu_read_lock is taken and released every iteration, just like the
spin lock, which means we're not protected against concurrent
insertions into the xarray. This is fine because we rely on
folio->private to detect if there are any ebs remaining in the folio.
There is already some precedent for this with find_extent_buffer_nolock,
which loads an extent buffer from the xarray with only rcu_read_lock.
lockdep warning:
=====================================================
WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
6.16.0-0_fbk701_debug_rc0_123_g4c06e63b9203 #1 Tainted: G E N
-----------------------------------------------------
kswapd0/66 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
ffff000011ffd600 (&eb->refs_lock){+.+.}-{3:3}, at: try_release_extent_buffer+0x18c/0x560
and this task is already holding:
ffff0000c1d91b88 (&buffer_xa_class){-.-.}-{3:3}, at: try_release_extent_buffer+0x13c/0x560
which would create a new lock dependency:
(&buffer_xa_class){-.-.}-{3:3} -> (&eb->refs_lock){+.+.}-{3:3}
but this new dependency connects a HARDIRQ-irq-safe lock:
(&buffer_xa_class){-.-.}-{3:3}
... which became HARDIRQ-irq-safe at:
lock_acquire+0x178/0x358
_raw_spin_lock_irqsave+0x60/0x88
buffer_tree_clear_mark+0xc4/0x160
end_bbio_meta_write+0x238/0x398
btrfs_bio_end_io+0x1f8/0x330
btrfs_orig_write_end_io+0x1c4/0x2c0
bio_endio+0x63c/0x678
blk_update_request+0x1c4/0xa00
blk_mq_end_request+0x54/0x88
virtblk_request_done+0x124/0x1d0
blk_mq_complete_request+0x84/0xa0
virtblk_done+0x130/0x238
vring_interrupt+0x130/0x288
__handle_irq_event_percpu+0x1e8/0x708
handle_irq_event+0x98/0x1b0
handle_fasteoi_irq+0x264/0x7c0
generic_handle_domain_irq+0xa4/0x108
gic_handle_irq+0x7c/0x1a0
do_interrupt_handler+0xe4/0x148
el1_interrupt+0x30/0x50
el1h_64_irq_handler+0x14/0x20
el1h_64_irq+0x6c/0x70
_raw_spin_unlock_irq+0x38/0x70
__run_timer_base+0xdc/0x5e0
run_timer_softirq+0xa0/0x138
handle_softirqs.llvm.13542289750107964195+0x32c/0xbd0
____do_softirq.llvm.17674514681856217165+0x18/0x28
call_on_irq_stack+0x24/0x30
__irq_exit_rcu+0x164/0x430
irq_exit_rcu+0x18/0x88
el1_interrupt+0x34/0x50
el1h_64_irq_handler+0x14/0x20
el1h_64_irq+0x6c/0x70
arch_local_irq_enable+0x4/0x8
do_idle+0x1a0/0x3b8
cpu_startup_entry+0x60/0x80
rest_init+0x204/0x228
start_kernel+0x394/0x3f0
__primary_switched+0x8c/0x8958
to a HARDIRQ-irq-unsafe lock:
(&eb->refs_lock){+.+.}-{3:3}
... which became HARDIRQ-irq-unsafe at:
...
lock_acquire+0x178/0x358
_raw_spin_lock+0x4c/0x68
free_extent_buffer_stale+0x2c/0x170
btrfs_read_sys_array+0x1b0/0x338
open_ctree+0xeb0/0x1df8
btrfs_get_tree+0xb60/0x1110
vfs_get_tree+0x8c/0x250
fc_mount+0x20/0x98
btrfs_get_tree+0x4a4/0x1110
vfs_get_tree+0x8c/0x250
do_new_mount+0x1e0/0x6c0
path_mount+0x4ec/0xa58
__arm64_sys_mount+0x370/0x490
invoke_syscall+0x6c/0x208
el0_svc_common+0x14c/0x1b8
do_el0_svc+0x4c/0x60
el0_svc+0x4c/0x160
el0t_64_sync_handler+0x70/0x100
el0t_64_sync+0x168/0x170
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&eb->refs_lock);
local_irq_disable();
lock(&buffer_xa_class);
lock(&eb->refs_lock);
<Interrupt>
lock(&buffer_xa_class);
*** DEADLOCK ***
2 locks held by kswapd0/66:
#0: ffff800085506e40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0xe8/0xe50
#1: ffff0000c1d91b88 (&buffer_xa_class){-.-.}-{3:3}, at: try_release_extent_buffer+0x13c/0x560
Link: https://www.kernel.org/doc/Documentation/locking/lockdep-design.rst#:~:text…
Fixes: 19d7f65f032f ("btrfs: convert the buffer_radix to an xarray")
CC: stable(a)vger.kernel.org # 6.16+
Reviewed-by: Boris Burkov <boris(a)bur.io>
Reviewed-by: Qu Wenruo <wqu(a)suse.com>
Signed-off-by: Leo Martins <loemra.dev(a)gmail.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 835b0deef9bb..f23d75986947 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -4331,15 +4331,18 @@ static int try_release_subpage_extent_buffer(struct folio *folio)
unsigned long end = index + (PAGE_SIZE >> fs_info->nodesize_bits) - 1;
int ret;
- xa_lock_irq(&fs_info->buffer_tree);
+ rcu_read_lock();
xa_for_each_range(&fs_info->buffer_tree, index, eb, start, end) {
/*
* The same as try_release_extent_buffer(), to ensure the eb
* won't disappear out from under us.
*/
spin_lock(&eb->refs_lock);
+ rcu_read_unlock();
+
if (refcount_read(&eb->refs) != 1 || extent_buffer_under_io(eb)) {
spin_unlock(&eb->refs_lock);
+ rcu_read_lock();
continue;
}
@@ -4358,11 +4361,10 @@ static int try_release_subpage_extent_buffer(struct folio *folio)
* check the folio private at the end. And
* release_extent_buffer() will release the refs_lock.
*/
- xa_unlock_irq(&fs_info->buffer_tree);
release_extent_buffer(eb);
- xa_lock_irq(&fs_info->buffer_tree);
+ rcu_read_lock();
}
- xa_unlock_irq(&fs_info->buffer_tree);
+ rcu_read_unlock();
/*
* Finally to check if we have cleared folio private, as if we have
@@ -4375,7 +4377,6 @@ static int try_release_subpage_extent_buffer(struct folio *folio)
ret = 0;
spin_unlock(&folio->mapping->i_private_lock);
return ret;
-
}
int try_release_extent_buffer(struct folio *folio)
The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable(a)vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 33e8f24b52d2796b8cfb28c19a1a7dd6476323a8
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081821-startling-skiing-ca6d@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 33e8f24b52d2796b8cfb28c19a1a7dd6476323a8 Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana(a)suse.com>
Date: Mon, 19 May 2025 11:07:29 +0100
Subject: [PATCH] btrfs: abort transaction on unexpected eb generation at
btrfs_copy_root()
If we find an unexpected generation for the extent buffer we are cloning
at btrfs_copy_root(), we just WARN_ON() and don't error out and abort the
transaction, meaning we allow to persist metadata with an unexpected
generation. Instead of warning only, abort the transaction and return
-EUCLEAN.
CC: stable(a)vger.kernel.org # 6.1+
Reviewed-by: Daniel Vacek <neelx(a)suse.com>
Reviewed-by: Qu Wenruo <wqu(a)suse.com>
Signed-off-by: Filipe Manana <fdmanana(a)suse.com>
Reviewed-by: David Sterba <dsterba(a)suse.com>
Signed-off-by: David Sterba <dsterba(a)suse.com>
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index ae6cd77282f5..a5ee6ce312cf 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -283,7 +283,14 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
write_extent_buffer_fsid(cow, fs_info->fs_devices->metadata_uuid);
- WARN_ON(btrfs_header_generation(buf) > trans->transid);
+ if (unlikely(btrfs_header_generation(buf) > trans->transid)) {
+ btrfs_tree_unlock(cow);
+ free_extent_buffer(cow);
+ ret = -EUCLEAN;
+ btrfs_abort_transaction(trans, ret);
+ return ret;
+ }
+
if (new_root_objectid == BTRFS_TREE_RELOC_OBJECTID) {
ret = btrfs_inc_ref(trans, root, cow, 1);
if (ret)