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FAILED: patch "[PATCH] xfs: fully decouple XFS_IBULK* flags from XFS_IWALK* flags" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

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);

4 weeks

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FAILED: patch "[PATCH] btrfs: send: use fallocate for hole punching with send stream" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

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

4 weeks

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[PATCH AUTOSEL 6.12 01/69] usb: xhci: print xhci->xhc_state when queue_command failed

by Sasha Levin

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

4 weeks

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FAILED: patch "[PATCH] btrfs: zoned: requeue to unused block group list if zone" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

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; }

4 weeks

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FAILED: patch "[PATCH] xfs: fully decouple XFS_IBULK* flags from XFS_IWALK* flags" failed to apply to 6.15-stable tree

by gregkh＠linuxfoundation.org

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);

4 weeks, 1 day

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FAILED: patch "[PATCH] btrfs: abort transaction on unexpected eb generation at" failed to apply to 6.1-stable tree

by gregkh＠linuxfoundation.org

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)

4 weeks, 1 day

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FAILED: patch "[PATCH] xfs: fully decouple XFS_IBULK* flags from XFS_IWALK* flags" failed to apply to 6.16-stable tree

by gregkh＠linuxfoundation.org

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);

4 weeks, 1 day

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FAILED: patch "[PATCH] btrfs: fix subpage deadlock in" failed to apply to 6.16-stable tree

by gregkh＠linuxfoundation.org

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)

4 weeks, 1 day

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FAILED: patch "[PATCH] btrfs: abort transaction on unexpected eb generation at" failed to apply to 6.6-stable tree

by gregkh＠linuxfoundation.org

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)

4 weeks, 1 day

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FAILED: patch "[PATCH] btrfs: abort transaction on unexpected eb generation at" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

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 33e8f24b52d2796b8cfb28c19a1a7dd6476323a8 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025081815-strut-suspend-7a53@gregkh' --subject-prefix 'PATCH 6.12.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)

4 weeks, 1 day

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