May 2025 - Linux-stable-mirror

[PATCH] ext4: inline: do not convert when writing to memory map

by Thadeu Lima de Souza Cascardo

inline data handling has a race between writing and writing to a memory map. When ext4_page_mkwrite is called, it calls ext4_convert_inline_data, which destroys the inline data, but if block allocation fails, restores the inline data. In that process, we could have: CPU1 CPU2 destroy_inline_data write_begin (does not see inline data) restory_inline_data write_end (sees inline data) This leads to bugs like the one below, as write_begin did not prepare for the case of inline data, which is expected by the write_end side of it. ------------[ cut here ]------------ kernel BUG at fs/ext4/inline.c:235! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 1 UID: 0 PID: 5838 Comm: syz-executor110 Not tainted 6.13.0-rc3-syzkaller-00209-g499551201b5f #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 RIP: 0010:ext4_write_inline_data fs/ext4/inline.c:235 [inline] RIP: 0010:ext4_write_inline_data_end+0xdc7/0xdd0 fs/ext4/inline.c:774 Code: 47 1d 8c e8 4b 3a 91 ff 90 0f 0b e8 63 7a 47 ff 48 8b 7c 24 10 48 c7 c6 e0 47 1d 8c e8 32 3a 91 ff 90 0f 0b e8 4a 7a 47 ff 90 <0f> 0b 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffc900031c7320 EFLAGS: 00010293 RAX: ffffffff8257f9a6 RBX: 000000000000005a RCX: ffff888012968000 RDX: 0000000000000000 RSI: 000000000000005a RDI: 000000000000005b RBP: ffffc900031c7448 R08: ffffffff8257ef87 R09: 1ffff11006806070 R10: dffffc0000000000 R11: ffffed1006806071 R12: 000000000000005a R13: dffffc0000000000 R14: ffff888076b65bd8 R15: 000000000000005b FS: 00007f5c6bacf6c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000a00 CR3: 0000000073fb6000 CR4: 0000000000350ef0 Call Trace: <TASK> generic_perform_write+0x6f8/0x990 mm/filemap.c:4070 ext4_buffered_write_iter+0xc5/0x350 fs/ext4/file.c:299 ext4_file_write_iter+0x892/0x1c50 iter_file_splice_write+0xbfc/0x1510 fs/splice.c:743 do_splice_from fs/splice.c:941 [inline] direct_splice_actor+0x11d/0x220 fs/splice.c:1164 splice_direct_to_actor+0x588/0xc80 fs/splice.c:1108 do_splice_direct_actor fs/splice.c:1207 [inline] do_splice_direct+0x289/0x3e0 fs/splice.c:1233 do_sendfile+0x564/0x8a0 fs/read_write.c:1363 __do_sys_sendfile64 fs/read_write.c:1424 [inline] __se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1410 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5c6bb18d09 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f5c6bacf218 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 RAX: ffffffffffffffda RBX: 00007f5c6bba0708 RCX: 00007f5c6bb18d09 RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000004 RBP: 00007f5c6bba0700 R08: 0000000000000000 R09: 0000000000000000 R10: 000080001d00c0d0 R11: 0000000000000246 R12: 00007f5c6bb6d620 R13: 00007f5c6bb6d0c0 R14: 0031656c69662f2e R15: 8088e3ad122bc192 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- This happens because ext4_page_mkwrite is not protected by the inode_lock. The xattr semaphore is not sufficient to protect inline data handling in a sane way, so we need to rely on the inode_lock. Adding the inode_lock to ext4_page_mkwrite is not an option, otherwise lock-ordering problems with mmap_lock may arise. The conversion inside ext4_page_mkwrite was introduced at commit 7b4cc9787fe3 ("ext4: evict inline data when writing to memory map"). This fixes a documented bug in the commit message, which suggests some alternatives fixes. The alternative of keeping the data inline is left as an exercise for the reader. Instead, block allocation still happens, just as it does right now. But removal of the inline data is only done when pages are written back. Fixes: 7b4cc9787fe3 ("ext4: evict inline data when writing to memory map") Reported-by: syzbot+0c89d865531d053abb2d(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=0c89d865531d053abb2d Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo(a)igalia.com> Cc: stable(a)vger.kernel.org --- fs/ext4/inode.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 94c7d2d828a64e42ded09c82497ed7617071aa19..38653d5c8b32ede2b130285ab13ef1e96b1ba783 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2620,8 +2620,7 @@ static int ext4_do_writepages(struct mpage_da_data *mpd) ret = PTR_ERR(handle); goto out_writepages; } - BUG_ON(ext4_test_inode_state(inode, - EXT4_STATE_MAY_INLINE_DATA)); + ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA); ext4_destroy_inline_data(handle, inode); ext4_journal_stop(handle); } @@ -6222,10 +6221,6 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) filemap_invalidate_lock_shared(mapping); - err = ext4_convert_inline_data(inode); - if (err) - goto out_ret; - /* * On data journalling we skip straight to the transaction handle: * there's no delalloc; page truncated will be checked later; the --- base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21 change-id: 20250519-ext4_inline_page_mkwrite-c42ca1f02295 Best regards, -- Thadeu Lima de Souza Cascardo <cascardo(a)igalia.com>

7 months

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Request to backport b3bee1e7c3f2b1b77182302c7b2131c804175870 (x86/boot: Compile boot code with -std=gnu11 too)

by Hendrik Donner

Hello, with gcc 15.1.1 i see the following build issue on 6.6.91: CC arch/x86/boot/a20.o In file included from ./include/uapi/linux/posix_types.h:5, from ./include/uapi/linux/types.h:14, from ./include/linux/types.h:6, from arch/x86/boot/boot.h:22, from arch/x86/boot/a20.c:14: ./include/linux/stddef.h:11:9: error: cannot use keyword 'false' as enumeration constant 11 | false = 0, | ^~~~~ ./include/linux/stddef.h:11:9: note: 'false' is a keyword with '-std=c23' onwards ./include/linux/types.h:35:33: error: 'bool' cannot be defined via 'typedef' 35 | typedef _Bool bool; | ^~~~ ./include/linux/types.h:35:33: note: 'bool' is a keyword with '-std=c23' onwards ./include/linux/types.h:35:1: warning: useless type name in empty declaration 35 | typedef _Bool bool; | ^~~~~~~ make[2]: *** [scripts/Makefile.build:243: arch/x86/boot/a20.o] Error 1 make[1]: *** [arch/x86/Makefile:284: bzImage] Error 2 Fixed by b3bee1e7c3f2b1b77182302c7b2131c804175870 (x86/boot: Compile boot code with -std=gnu11 too), which hasn't been backported yet. Should probably go into all stable trees. Regards, Hendrik

7 months

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[PATCH v5 0/4] media: uvcvideo: Introduce V4L2_META_FMT_UVC_MSXU_1_5 + other meta fixes

by Ricardo Ribalda

This series introduces a new metadata format for UVC cameras and adds a couple of improvements to the UVC metadata handling. Signed-off-by: Ricardo Ribalda <ribalda(a)chromium.org> --- Changes in v5: - Fix codestyle and kerneldoc warnings reported by media-ci - Link to v4: https://lore.kernel.org/r/20250403-uvc-meta-v4-0-877aa6475975@chromium.org Changes in v4: - Rename format to V4L2_META_FMT_UVC_MSXU_1_5 (Thanks Mauro) - Flag the new format with a quirk. - Autodetect MSXU devices. - Link to v3: https://lore.kernel.org/linux-media/20250313-uvc-metadata-v3-0-c467af869c60… Changes in v3: - Fix doc syntax errors. - Link to v2: https://lore.kernel.org/r/20250306-uvc-metadata-v2-0-7e939857cad5@chromium.… Changes in v2: - Add metadata invalid fix - Move doc note to a separate patch - Introuce V4L2_META_FMT_UVC_CUSTOM (thanks HdG!). - Link to v1: https://lore.kernel.org/r/20250226-uvc-metadata-v1-1-6cd6fe5ec2cb@chromium.… --- Ricardo Ribalda (4): media: uvcvideo: Do not mark valid metadata as invalid media: Documentation: Add note about UVCH length field media: uvcvideo: Introduce V4L2_META_FMT_UVC_MSXU_1_5 media: uvcvideo: Auto-set UVC_QUIRK_MSXU_META .../userspace-api/media/v4l/meta-formats.rst | 1 + .../media/v4l/metafmt-uvc-msxu-1-5.rst | 23 +++++ .../userspace-api/media/v4l/metafmt-uvc.rst | 4 +- MAINTAINERS | 1 + drivers/media/usb/uvc/uvc_metadata.c | 97 ++++++++++++++++++++-- drivers/media/usb/uvc/uvc_video.c | 12 +-- drivers/media/usb/uvc/uvcvideo.h | 1 + drivers/media/v4l2-core/v4l2-ioctl.c | 1 + include/linux/usb/uvc.h | 3 + include/uapi/linux/videodev2.h | 1 + 10 files changed, 131 insertions(+), 13 deletions(-) --- base-commit: 4e82c87058f45e79eeaa4d5bcc3b38dd3dce7209 change-id: 20250403-uvc-meta-e556773d12ae Best regards, -- Ricardo Ribalda <ribalda(a)chromium.org>

7 months

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[PATCH 6.1 1/1] erofs: get rid of z_erofs_fill_inode()

by d.privalov

From: Gao Xiang <hsiangkao(a)linux.alibaba.com> commit 4fdadd5b0f0c723c812842454f8cca1619f2e731 upstream. Prior to big pclusters, non-compact compression indexes could have empty headers. Let's just avoid the legacy path since it can be handled properly as a specific compression header with z_erofs_fill_inode_lazy() too. Tested with erofs-utils exist versions. Signed-off-by: Gao Xiang <hsiangkao(a)linux.alibaba.com> Reviewed-by: Yue Hu <huyue2(a)coolpad.com> Reviewed-by: Chao Yu <chao(a)kernel.org> Link: https://lore.kernel.org/r/20230413092241.73829-1-hsiangkao@linux.alibaba.com Signed-off-by: Dmitriy Privalov <d.privalov(a)omp.ru> --- fs/erofs/inode.c | 12 ++++++++---- fs/erofs/internal.h | 2 -- fs/erofs/zmap.c | 18 ------------------ 3 files changed, 8 insertions(+), 24 deletions(-) diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c index 7dcf350b9fef9..550b93fd12031 100644 --- a/fs/erofs/inode.c +++ b/fs/erofs/inode.c @@ -283,11 +283,15 @@ static int erofs_fill_inode(struct inode *inode) } if (erofs_inode_is_data_compressed(vi->datalayout)) { +#ifdef CONFIG_EROFS_FS_ZIP if (!erofs_is_fscache_mode(inode->i_sb) && - inode->i_sb->s_blocksize_bits == PAGE_SHIFT) - err = z_erofs_fill_inode(inode); - else - err = -EOPNOTSUPP; + inode->i_sb->s_blocksize_bits == PAGE_SHIFT) { + inode->i_mapping->a_ops = &z_erofs_aops; + err = 0; + goto out_unlock; + } +#endif + err = -EOPNOTSUPP; goto out_unlock; } inode->i_mapping->a_ops = &erofs_raw_access_aops; diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h index d7cd1e619d46f..161317f8fe266 100644 --- a/fs/erofs/internal.h +++ b/fs/erofs/internal.h @@ -425,12 +425,10 @@ enum { extern const struct iomap_ops z_erofs_iomap_report_ops; #ifdef CONFIG_EROFS_FS_ZIP -int z_erofs_fill_inode(struct inode *inode); int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map, int flags); #else -static inline int z_erofs_fill_inode(struct inode *inode) { return -EOPNOTSUPP; } static inline int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map, int flags) diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c index 2cd70cf4c8b27..b030a04bdd283 100644 --- a/fs/erofs/zmap.c +++ b/fs/erofs/zmap.c @@ -7,24 +7,6 @@ #include <asm/unaligned.h> #include <trace/events/erofs.h> -int z_erofs_fill_inode(struct inode *inode) -{ - struct erofs_inode *const vi = EROFS_I(inode); - struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb); - - if (!erofs_sb_has_big_pcluster(sbi) && - !erofs_sb_has_ztailpacking(sbi) && !erofs_sb_has_fragments(sbi) && - vi->datalayout == EROFS_INODE_COMPRESSED_FULL) { - vi->z_advise = 0; - vi->z_algorithmtype[0] = 0; - vi->z_algorithmtype[1] = 0; - vi->z_logical_clusterbits = inode->i_sb->s_blocksize_bits; - set_bit(EROFS_I_Z_INITED_BIT, &vi->flags); - } - inode->i_mapping->a_ops = &z_erofs_aops; - return 0; -} - struct z_erofs_maprecorder { struct inode *inode; struct erofs_map_blocks *map; -- 2.34.1

7 months

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Re: [PATCH v1] virtio_blk: Fix disk deletion hang on device surprise removal

by Stefan Hajnoczi

On Wed, May 21, 2025 at 06:37:41AM +0000, Parav Pandit wrote: > When the PCI device is surprise removed, requests may not complete > the device as the VQ is marked as broken. Due to this, the disk > deletion hangs. > > Fix it by aborting the requests when the VQ is broken. > > With this fix now fio completes swiftly. > An alternative of IO timeout has been considered, however > when the driver knows about unresponsive block device, swiftly clearing > them enables users and upper layers to react quickly. > > Verified with multiple device unplug iterations with pending requests in > virtio used ring and some pending with the device. > > Fixes: 43bb40c5b926 ("virtio_pci: Support surprise removal of virtio pci device") > Cc: stable(a)vger.kernel.org > Reported-by: lirongqing(a)baidu.com > Closes: https://lore.kernel.org/virtualization/c45dd68698cd47238c55fb73ca9b4741@bai… > Reviewed-by: Max Gurtovoy <mgurtovoy(a)nvidia.com> > Reviewed-by: Israel Rukshin <israelr(a)nvidia.com> > Signed-off-by: Parav Pandit <parav(a)nvidia.com> > --- > changelog: > v0->v1: > - Fixed comments from Stefan to rename a cleanup function > - Improved logic for handling any outstanding requests > in bio layer > - improved cancel callback to sync with ongoing done() > > --- > drivers/block/virtio_blk.c | 95 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 95 insertions(+) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index 7cffea01d868..5212afdbd3c7 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -435,6 +435,13 @@ static blk_status_t virtio_queue_rq(struct blk_mq_hw_ctx *hctx, > blk_status_t status; > int err; > > + /* Immediately fail all incoming requests if the vq is broken. > + * Once the queue is unquiesced, upper block layer flushes any pending > + * queued requests; fail them right away. > + */ > + if (unlikely(virtqueue_is_broken(vblk->vqs[qid].vq))) > + return BLK_STS_IOERR; > + > status = virtblk_prep_rq(hctx, vblk, req, vbr); > if (unlikely(status)) > return status; > @@ -508,6 +515,11 @@ static void virtio_queue_rqs(struct rq_list *rqlist) > while ((req = rq_list_pop(rqlist))) { > struct virtio_blk_vq *this_vq = get_virtio_blk_vq(req->mq_hctx); > > + if (unlikely(virtqueue_is_broken(this_vq->vq))) { > + rq_list_add_tail(&requeue_list, req); > + continue; > + } > + > if (vq && vq != this_vq) > virtblk_add_req_batch(vq, &submit_list); > vq = this_vq; > @@ -1554,6 +1566,87 @@ static int virtblk_probe(struct virtio_device *vdev) > return err; > } > > +static bool virtblk_request_cancel(struct request *rq, void *data) > +{ > + struct virtblk_req *vbr = blk_mq_rq_to_pdu(rq); > + struct virtio_blk *vblk = data; > + struct virtio_blk_vq *vq; > + unsigned long flags; > + > + vq = &vblk->vqs[rq->mq_hctx->queue_num]; > + > + spin_lock_irqsave(&vq->lock, flags); > + > + vbr->in_hdr.status = VIRTIO_BLK_S_IOERR; > + if (blk_mq_request_started(rq) && !blk_mq_request_completed(rq)) > + blk_mq_complete_request(rq); > + > + spin_unlock_irqrestore(&vq->lock, flags); > + return true; > +} > + > +static void virtblk_broken_device_cleanup(struct virtio_blk *vblk) > +{ > + struct request_queue *q = vblk->disk->queue; > + > + if (!virtqueue_is_broken(vblk->vqs[0].vq)) > + return; Can a subset of virtqueues be broken? If so, then this code doesn't handle it. > + > + /* Start freezing the queue, so that new requests keeps waitng at the s/waitng/waiting/ > + * door of bio_queue_enter(). We cannot fully freeze the queue because > + * freezed queue is an empty queue and there are pending requests, so > + * only start freezing it. > + */ > + blk_freeze_queue_start(q); > + > + /* When quiescing completes, all ongoing dispatches have completed > + * and no new dispatch will happen towards the driver. > + * This ensures that later when cancel is attempted, then are not > + * getting processed by the queue_rq() or queue_rqs() handlers. > + */ > + blk_mq_quiesce_queue(q); > + > + /* > + * Synchronize with any ongoing VQ callbacks, effectively quiescing > + * the device and preventing it from completing further requests > + * to the block layer. Any outstanding, incomplete requests will be > + * completed by virtblk_request_cancel(). > + */ > + virtio_synchronize_cbs(vblk->vdev); > + > + /* At this point, no new requests can enter the queue_rq() and > + * completion routine will not complete any new requests either for the > + * broken vq. Hence, it is safe to cancel all requests which are > + * started. > + */ > + blk_mq_tagset_busy_iter(&vblk->tag_set, virtblk_request_cancel, vblk); Although virtio_synchronize_cbs() was called, a broken/malicious device can still raise IRQs. Would that lead to use-after-free or similar undefined behavior for requests that have been submitted to the device? It seems safer to reset the device before marking the requests as failed. > + blk_mq_tagset_wait_completed_request(&vblk->tag_set); > + > + /* All pending requests are cleaned up. Time to resume so that disk > + * deletion can be smooth. Start the HW queues so that when queue is > + * unquiesced requests can again enter the driver. > + */ > + blk_mq_start_stopped_hw_queues(q, true); > + > + /* Unquiescing will trigger dispatching any pending requests to the > + * driver which has crossed bio_queue_enter() to the driver. > + */ > + blk_mq_unquiesce_queue(q); > + > + /* Wait for all pending dispatches to terminate which may have been > + * initiated after unquiescing. > + */ > + blk_mq_freeze_queue_wait(q); > + > + /* Mark the disk dead so that once queue unfreeze, the requests > + * waiting at the door of bio_queue_enter() can be aborted right away. > + */ > + blk_mark_disk_dead(vblk->disk); > + > + /* Unfreeze the queue so that any waiting requests will be aborted. */ > + blk_mq_unfreeze_queue_nomemrestore(q); > +} > + > static void virtblk_remove(struct virtio_device *vdev) > { > struct virtio_blk *vblk = vdev->priv; > @@ -1561,6 +1654,8 @@ static void virtblk_remove(struct virtio_device *vdev) > /* Make sure no work handler is accessing the device. */ > flush_work(&vblk->config_work); > > + virtblk_broken_device_cleanup(vblk); > + > del_gendisk(vblk->disk); > blk_mq_free_tag_set(&vblk->tag_set); > > -- > 2.34.1 >

7 months

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FAILED: patch "[PATCH] kasan: avoid sleepable page allocation from atomic context" 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 b6ea95a34cbd014ab6ade4248107b86b0aaf2d6c # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025052647-paprika-unsterile-4753@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From b6ea95a34cbd014ab6ade4248107b86b0aaf2d6c Mon Sep 17 00:00:00 2001 From: Alexander Gordeev <agordeev(a)linux.ibm.com> Date: Thu, 15 May 2025 15:55:38 +0200 Subject: [PATCH] kasan: avoid sleepable page allocation from atomic context apply_to_pte_range() enters the lazy MMU mode and then invokes kasan_populate_vmalloc_pte() callback on each page table walk iteration. However, the callback can go into sleep when trying to allocate a single page, e.g. if an architecutre disables preemption on lazy MMU mode enter. On s390 if make arch_enter_lazy_mmu_mode() -> preempt_enable() and arch_leave_lazy_mmu_mode() -> preempt_disable(), such crash occurs: [ 0.663336] BUG: sleeping function called from invalid context at ./include/linux/sched/mm.h:321 [ 0.663348] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2, name: kthreadd [ 0.663358] preempt_count: 1, expected: 0 [ 0.663366] RCU nest depth: 0, expected: 0 [ 0.663375] no locks held by kthreadd/2. [ 0.663383] Preemption disabled at: [ 0.663386] [<0002f3284cbb4eda>] apply_to_pte_range+0xfa/0x4a0 [ 0.663405] CPU: 0 UID: 0 PID: 2 Comm: kthreadd Not tainted 6.15.0-rc5-gcc-kasan-00043-gd76bb1ebb558-dirty #162 PREEMPT [ 0.663408] Hardware name: IBM 3931 A01 701 (KVM/Linux) [ 0.663409] Call Trace: [ 0.663410] [<0002f3284c385f58>] dump_stack_lvl+0xe8/0x140 [ 0.663413] [<0002f3284c507b9e>] __might_resched+0x66e/0x700 [ 0.663415] [<0002f3284cc4f6c0>] __alloc_frozen_pages_noprof+0x370/0x4b0 [ 0.663419] [<0002f3284ccc73c0>] alloc_pages_mpol+0x1a0/0x4a0 [ 0.663421] [<0002f3284ccc8518>] alloc_frozen_pages_noprof+0x88/0xc0 [ 0.663424] [<0002f3284ccc8572>] alloc_pages_noprof+0x22/0x120 [ 0.663427] [<0002f3284cc341ac>] get_free_pages_noprof+0x2c/0xc0 [ 0.663429] [<0002f3284cceba70>] kasan_populate_vmalloc_pte+0x50/0x120 [ 0.663433] [<0002f3284cbb4ef8>] apply_to_pte_range+0x118/0x4a0 [ 0.663435] [<0002f3284cbc7c14>] apply_to_pmd_range+0x194/0x3e0 [ 0.663437] [<0002f3284cbc99be>] __apply_to_page_range+0x2fe/0x7a0 [ 0.663440] [<0002f3284cbc9e88>] apply_to_page_range+0x28/0x40 [ 0.663442] [<0002f3284ccebf12>] kasan_populate_vmalloc+0x82/0xa0 [ 0.663445] [<0002f3284cc1578c>] alloc_vmap_area+0x34c/0xc10 [ 0.663448] [<0002f3284cc1c2a6>] __get_vm_area_node+0x186/0x2a0 [ 0.663451] [<0002f3284cc1e696>] __vmalloc_node_range_noprof+0x116/0x310 [ 0.663454] [<0002f3284cc1d950>] __vmalloc_node_noprof+0xd0/0x110 [ 0.663457] [<0002f3284c454b88>] alloc_thread_stack_node+0xf8/0x330 [ 0.663460] [<0002f3284c458d56>] dup_task_struct+0x66/0x4d0 [ 0.663463] [<0002f3284c45be90>] copy_process+0x280/0x4b90 [ 0.663465] [<0002f3284c460940>] kernel_clone+0xd0/0x4b0 [ 0.663467] [<0002f3284c46115e>] kernel_thread+0xbe/0xe0 [ 0.663469] [<0002f3284c4e440e>] kthreadd+0x50e/0x7f0 [ 0.663472] [<0002f3284c38c04a>] __ret_from_fork+0x8a/0xf0 [ 0.663475] [<0002f3284ed57ff2>] ret_from_fork+0xa/0x38 Instead of allocating single pages per-PTE, bulk-allocate the shadow memory prior to applying kasan_populate_vmalloc_pte() callback on a page range. Link: https://lkml.kernel.org/r/c61d3560297c93ed044f0b1af085610353a06a58.17473169… Fixes: 3c5c3cfb9ef4 ("kasan: support backing vmalloc space with real shadow memory") Signed-off-by: Alexander Gordeev <agordeev(a)linux.ibm.com> Suggested-by: Andrey Ryabinin <ryabinin.a.a(a)gmail.com> Reviewed-by: Harry Yoo <harry.yoo(a)oracle.com> Cc: Daniel Axtens <dja(a)axtens.net> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index 88d1c9dcb507..d2c70cd2afb1 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -292,33 +292,99 @@ void __init __weak kasan_populate_early_vm_area_shadow(void *start, { } +struct vmalloc_populate_data { + unsigned long start; + struct page **pages; +}; + static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, - void *unused) + void *_data) { - unsigned long page; + struct vmalloc_populate_data *data = _data; + struct page *page; pte_t pte; + int index; if (likely(!pte_none(ptep_get(ptep)))) return 0; - page = __get_free_page(GFP_KERNEL); - if (!page) - return -ENOMEM; - - __memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); - pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); + index = PFN_DOWN(addr - data->start); + page = data->pages[index]; + __memset(page_to_virt(page), KASAN_VMALLOC_INVALID, PAGE_SIZE); + pte = pfn_pte(page_to_pfn(page), PAGE_KERNEL); spin_lock(&init_mm.page_table_lock); if (likely(pte_none(ptep_get(ptep)))) { set_pte_at(&init_mm, addr, ptep, pte); - page = 0; + data->pages[index] = NULL; } spin_unlock(&init_mm.page_table_lock); - if (page) - free_page(page); + return 0; } +static void ___free_pages_bulk(struct page **pages, int nr_pages) +{ + int i; + + for (i = 0; i < nr_pages; i++) { + if (pages[i]) { + __free_pages(pages[i], 0); + pages[i] = NULL; + } + } +} + +static int ___alloc_pages_bulk(struct page **pages, int nr_pages) +{ + unsigned long nr_populated, nr_total = nr_pages; + struct page **page_array = pages; + + while (nr_pages) { + nr_populated = alloc_pages_bulk(GFP_KERNEL, nr_pages, pages); + if (!nr_populated) { + ___free_pages_bulk(page_array, nr_total - nr_pages); + return -ENOMEM; + } + pages += nr_populated; + nr_pages -= nr_populated; + } + + return 0; +} + +static int __kasan_populate_vmalloc(unsigned long start, unsigned long end) +{ + unsigned long nr_pages, nr_total = PFN_UP(end - start); + struct vmalloc_populate_data data; + int ret = 0; + + data.pages = (struct page **)__get_free_page(GFP_KERNEL | __GFP_ZERO); + if (!data.pages) + return -ENOMEM; + + while (nr_total) { + nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0])); + ret = ___alloc_pages_bulk(data.pages, nr_pages); + if (ret) + break; + + data.start = start; + ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE, + kasan_populate_vmalloc_pte, &data); + ___free_pages_bulk(data.pages, nr_pages); + if (ret) + break; + + start += nr_pages * PAGE_SIZE; + nr_total -= nr_pages; + } + + free_page((unsigned long)data.pages); + + return ret; +} + int kasan_populate_vmalloc(unsigned long addr, unsigned long size) { unsigned long shadow_start, shadow_end; @@ -348,9 +414,7 @@ int kasan_populate_vmalloc(unsigned long addr, unsigned long size) shadow_start = PAGE_ALIGN_DOWN(shadow_start); shadow_end = PAGE_ALIGN(shadow_end); - ret = apply_to_page_range(&init_mm, shadow_start, - shadow_end - shadow_start, - kasan_populate_vmalloc_pte, NULL); + ret = __kasan_populate_vmalloc(shadow_start, shadow_end); if (ret) return ret;

7 months

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[PATCH] mm/hugetlb: fix kernel NULL pointer dereference when replacing free hugetlb folios

by yangge1116＠126.com

From: Ge Yang <yangge1116(a)126.com> A kernel crash was observed when replacing free hugetlb folios: BUG: kernel NULL pointer dereference, address: 0000000000000028 PGD 0 P4D 0 Oops: Oops: 0000 [#1] SMP NOPTI CPU: 28 UID: 0 PID: 29639 Comm: test_cma.sh Tainted 6.15.0-rc6-zp #41 PREEMPT(voluntary) RIP: 0010:alloc_and_dissolve_hugetlb_folio+0x1d/0x1f0 RSP: 0018:ffffc9000b30fa90 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000342cca RCX: ffffea0043000000 RDX: ffffc9000b30fb08 RSI: ffffea0043000000 RDI: 0000000000000000 RBP: ffffc9000b30fb20 R08: 0000000000001000 R09: 0000000000000000 R10: ffff88886f92eb00 R11: 0000000000000000 R12: ffffea0043000000 R13: 0000000000000000 R14: 00000000010c0200 R15: 0000000000000004 FS: 00007fcda5f14740(0000) GS:ffff8888ec1d8000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000028 CR3: 0000000391402000 CR4: 0000000000350ef0 Call Trace: <TASK> replace_free_hugepage_folios+0xb6/0x100 alloc_contig_range_noprof+0x18a/0x590 ? srso_return_thunk+0x5/0x5f ? down_read+0x12/0xa0 ? srso_return_thunk+0x5/0x5f cma_range_alloc.constprop.0+0x131/0x290 __cma_alloc+0xcf/0x2c0 cma_alloc_write+0x43/0xb0 simple_attr_write_xsigned.constprop.0.isra.0+0xb2/0x110 debugfs_attr_write+0x46/0x70 full_proxy_write+0x62/0xa0 vfs_write+0xf8/0x420 ? srso_return_thunk+0x5/0x5f ? filp_flush+0x86/0xa0 ? srso_return_thunk+0x5/0x5f ? filp_close+0x1f/0x30 ? srso_return_thunk+0x5/0x5f ? do_dup2+0xaf/0x160 ? srso_return_thunk+0x5/0x5f ksys_write+0x65/0xe0 do_syscall_64+0x64/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e There is a potential race between __update_and_free_hugetlb_folio() and replace_free_hugepage_folios(): CPU1 CPU2 __update_and_free_hugetlb_folio replace_free_hugepage_folios folio_test_hugetlb(folio) -- It's still hugetlb folio. __folio_clear_hugetlb(folio) hugetlb_free_folio(folio) h = folio_hstate(folio) -- Here, h is NULL pointer When the above race condition occurs, folio_hstate(folio) returns NULL, and subsequent access to this NULL pointer will cause the system to crash. To resolve this issue, execute folio_hstate(folio) under the protection of the hugetlb_lock lock, ensuring that folio_hstate(folio) does not return NULL. Fixes: 04f13d241b8b ("mm: replace free hugepage folios after migration") Signed-off-by: Ge Yang <yangge1116(a)126.com> Cc: <stable(a)vger.kernel.org> --- mm/hugetlb.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 3d3ca6b..6c2e007 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2924,12 +2924,20 @@ int replace_free_hugepage_folios(unsigned long start_pfn, unsigned long end_pfn) while (start_pfn < end_pfn) { folio = pfn_folio(start_pfn); + + /* + * The folio might have been dissolved from under our feet, so make sure + * to carefully check the state under the lock. + */ + spin_lock_irq(&hugetlb_lock); if (folio_test_hugetlb(folio)) { h = folio_hstate(folio); } else { + spin_unlock_irq(&hugetlb_lock); start_pfn++; continue; } + spin_unlock_irq(&hugetlb_lock); if (!folio_ref_count(folio)) { ret = alloc_and_dissolve_hugetlb_folio(h, folio, -- 2.7.4

7 months

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0 0

FAILED: patch "[PATCH] mm: fix copy_vma() error handling for hugetlb mappings" failed to apply to 5.10-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.10-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-5.10.y git checkout FETCH_HEAD git cherry-pick -x ee40c9920ac286c5bfe7c811e66ff899266d2582 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025052659-snugly-tag-6f43@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From ee40c9920ac286c5bfe7c811e66ff899266d2582 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ricardo=20Ca=C3=B1uelo=20Navarro?= <rcn(a)igalia.com> Date: Fri, 23 May 2025 14:19:10 +0200 Subject: [PATCH] mm: fix copy_vma() error handling for hugetlb mappings MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If, during a mremap() operation for a hugetlb-backed memory mapping, copy_vma() fails after the source vma has been duplicated and opened (ie. vma_link() fails), the error is handled by closing the new vma. This updates the hugetlbfs reservation counter of the reservation map which at this point is referenced by both the source vma and the new copy. As a result, once the new vma has been freed and copy_vma() returns, the reservation counter for the source vma will be incorrect. This patch addresses this corner case by clearing the hugetlb private page reservation reference for the new vma and decrementing the reference before closing the vma, so that vma_close() won't update the reservation counter. This is also what copy_vma_and_data() does with the source vma if copy_vma() succeeds, so a helper function has been added to do the fixup in both functions. The issue was reported by a private syzbot instance and can be reproduced using the C reproducer in [1]. It's also a possible duplicate of public syzbot report [2]. The WARNING report is: ============================================================ page_counter underflow: -1024 nr_pages=1024 WARNING: CPU: 0 PID: 3287 at mm/page_counter.c:61 page_counter_cancel+0xf6/0x120 Modules linked in: CPU: 0 UID: 0 PID: 3287 Comm: repro__WARNING_ Not tainted 6.15.0-rc7+ #54 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014 RIP: 0010:page_counter_cancel+0xf6/0x120 Code: ff 5b 41 5e 41 5f 5d c3 cc cc cc cc e8 f3 4f 8f ff c6 05 64 01 27 06 01 48 c7 c7 60 15 f8 85 48 89 de 4c 89 fa e8 2a a7 51 ff <0f> 0b e9 66 ff ff ff 44 89 f9 80 e1 07 38 c1 7c 9d 4c 81 RSP: 0018:ffffc900025df6a0 EFLAGS: 00010246 RAX: 2edfc409ebb44e00 RBX: fffffffffffffc00 RCX: ffff8880155f0000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: dffffc0000000000 R08: ffffffff81c4a23c R09: 1ffff1100330482a R10: dffffc0000000000 R11: ffffed100330482b R12: 0000000000000000 R13: ffff888058a882c0 R14: ffff888058a882c0 R15: 0000000000000400 FS: 0000000000000000(0000) GS:ffff88808fc53000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004b33e0 CR3: 00000000076d6000 CR4: 00000000000006f0 Call Trace: <TASK> page_counter_uncharge+0x33/0x80 hugetlb_cgroup_uncharge_counter+0xcb/0x120 hugetlb_vm_op_close+0x579/0x960 ? __pfx_hugetlb_vm_op_close+0x10/0x10 remove_vma+0x88/0x130 exit_mmap+0x71e/0xe00 ? __pfx_exit_mmap+0x10/0x10 ? __mutex_unlock_slowpath+0x22e/0x7f0 ? __pfx_exit_aio+0x10/0x10 ? __up_read+0x256/0x690 ? uprobe_clear_state+0x274/0x290 ? mm_update_next_owner+0xa9/0x810 __mmput+0xc9/0x370 exit_mm+0x203/0x2f0 ? __pfx_exit_mm+0x10/0x10 ? taskstats_exit+0x32b/0xa60 do_exit+0x921/0x2740 ? do_raw_spin_lock+0x155/0x3b0 ? __pfx_do_exit+0x10/0x10 ? __pfx_do_raw_spin_lock+0x10/0x10 ? _raw_spin_lock_irq+0xc5/0x100 do_group_exit+0x20c/0x2c0 get_signal+0x168c/0x1720 ? __pfx_get_signal+0x10/0x10 ? schedule+0x165/0x360 arch_do_signal_or_restart+0x8e/0x7d0 ? __pfx_arch_do_signal_or_restart+0x10/0x10 ? __pfx___se_sys_futex+0x10/0x10 syscall_exit_to_user_mode+0xb8/0x2c0 do_syscall_64+0x75/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x422dcd Code: Unable to access opcode bytes at 0x422da3. RSP: 002b:00007ff266cdb208 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007ff266cdbcdc RCX: 0000000000422dcd RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00000000004c7bec RBP: 00007ff266cdb220 R08: 203a6362696c6720 R09: 203a6362696c6720 R10: 0000200000c00000 R11: 0000000000000246 R12: ffffffffffffffd0 R13: 0000000000000002 R14: 00007ffe1cb5f520 R15: 00007ff266cbb000 </TASK> ============================================================ Link: https://lkml.kernel.org/r/20250523-warning_in_page_counter_cancel-v2-1-b6df… Link: https://people.igalia.com/rcn/kernel_logs/20250422__WARNING_in_page_counter… [1] Link: https://lore.kernel.org/all/67000a50.050a0220.49194.048d.GAE@google.com/ [2] Signed-off-by: Ricardo Cañuelo Navarro <rcn(a)igalia.com> Suggested-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Reviewed-by: Liam R. Howlett <Liam.Howlett(a)oracle.com> Cc: Florent Revest <revest(a)google.com> Cc: Jann Horn <jannh(a)google.com> Cc: Oscar Salvador <osalvador(a)suse.de> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 8f3ac832ee7f..4861a7e304bb 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -275,6 +275,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma, bool is_hugetlb_entry_migration(pte_t pte); bool is_hugetlb_entry_hwpoisoned(pte_t pte); void hugetlb_unshare_all_pmds(struct vm_area_struct *vma); +void fixup_hugetlb_reservations(struct vm_area_struct *vma); #else /* !CONFIG_HUGETLB_PAGE */ @@ -468,6 +469,10 @@ static inline vm_fault_t hugetlb_fault(struct mm_struct *mm, static inline void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) { } +static inline void fixup_hugetlb_reservations(struct vm_area_struct *vma) +{ +} + #endif /* !CONFIG_HUGETLB_PAGE */ #ifndef pgd_write diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 55e6796b24d0..6a3cf7935c14 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1250,7 +1250,7 @@ void hugetlb_dup_vma_private(struct vm_area_struct *vma) /* * Reset and decrement one ref on hugepage private reservation. * Called with mm->mmap_lock writer semaphore held. - * This function should be only used by move_vma() and operate on + * This function should be only used by mremap and operate on * same sized vma. It should never come here with last ref on the * reservation. */ @@ -7939,3 +7939,17 @@ void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) hugetlb_unshare_pmds(vma, ALIGN(vma->vm_start, PUD_SIZE), ALIGN_DOWN(vma->vm_end, PUD_SIZE)); } + +/* + * For hugetlb, mremap() is an odd edge case - while the VMA copying is + * performed, we permit both the old and new VMAs to reference the same + * reservation. + * + * We fix this up after the operation succeeds, or if a newly allocated VMA + * is closed as a result of a failure to allocate memory. + */ +void fixup_hugetlb_reservations(struct vm_area_struct *vma) +{ + if (is_vm_hugetlb_page(vma)) + clear_vma_resv_huge_pages(vma); +} diff --git a/mm/mremap.c b/mm/mremap.c index 7db9da609c84..0d4948b720e2 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1188,8 +1188,7 @@ static int copy_vma_and_data(struct vma_remap_struct *vrm, mremap_userfaultfd_prep(new_vma, vrm->uf); } - if (is_vm_hugetlb_page(vma)) - clear_vma_resv_huge_pages(vma); + fixup_hugetlb_reservations(vma); /* Tell pfnmap has moved from this vma */ if (unlikely(vma->vm_flags & VM_PFNMAP)) diff --git a/mm/vma.c b/mm/vma.c index 839d12f02c88..a468d4c29c0c 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -1834,6 +1834,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, return new_vma; out_vma_link: + fixup_hugetlb_reservations(new_vma); vma_close(new_vma); if (new_vma->vm_file)

7 months

1
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FAILED: patch "[PATCH] mm: fix copy_vma() error handling for hugetlb mappings" failed to apply to 5.15-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x ee40c9920ac286c5bfe7c811e66ff899266d2582 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025052654-retired-handling-209f@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From ee40c9920ac286c5bfe7c811e66ff899266d2582 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ricardo=20Ca=C3=B1uelo=20Navarro?= <rcn(a)igalia.com> Date: Fri, 23 May 2025 14:19:10 +0200 Subject: [PATCH] mm: fix copy_vma() error handling for hugetlb mappings MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If, during a mremap() operation for a hugetlb-backed memory mapping, copy_vma() fails after the source vma has been duplicated and opened (ie. vma_link() fails), the error is handled by closing the new vma. This updates the hugetlbfs reservation counter of the reservation map which at this point is referenced by both the source vma and the new copy. As a result, once the new vma has been freed and copy_vma() returns, the reservation counter for the source vma will be incorrect. This patch addresses this corner case by clearing the hugetlb private page reservation reference for the new vma and decrementing the reference before closing the vma, so that vma_close() won't update the reservation counter. This is also what copy_vma_and_data() does with the source vma if copy_vma() succeeds, so a helper function has been added to do the fixup in both functions. The issue was reported by a private syzbot instance and can be reproduced using the C reproducer in [1]. It's also a possible duplicate of public syzbot report [2]. The WARNING report is: ============================================================ page_counter underflow: -1024 nr_pages=1024 WARNING: CPU: 0 PID: 3287 at mm/page_counter.c:61 page_counter_cancel+0xf6/0x120 Modules linked in: CPU: 0 UID: 0 PID: 3287 Comm: repro__WARNING_ Not tainted 6.15.0-rc7+ #54 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014 RIP: 0010:page_counter_cancel+0xf6/0x120 Code: ff 5b 41 5e 41 5f 5d c3 cc cc cc cc e8 f3 4f 8f ff c6 05 64 01 27 06 01 48 c7 c7 60 15 f8 85 48 89 de 4c 89 fa e8 2a a7 51 ff <0f> 0b e9 66 ff ff ff 44 89 f9 80 e1 07 38 c1 7c 9d 4c 81 RSP: 0018:ffffc900025df6a0 EFLAGS: 00010246 RAX: 2edfc409ebb44e00 RBX: fffffffffffffc00 RCX: ffff8880155f0000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: dffffc0000000000 R08: ffffffff81c4a23c R09: 1ffff1100330482a R10: dffffc0000000000 R11: ffffed100330482b R12: 0000000000000000 R13: ffff888058a882c0 R14: ffff888058a882c0 R15: 0000000000000400 FS: 0000000000000000(0000) GS:ffff88808fc53000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004b33e0 CR3: 00000000076d6000 CR4: 00000000000006f0 Call Trace: <TASK> page_counter_uncharge+0x33/0x80 hugetlb_cgroup_uncharge_counter+0xcb/0x120 hugetlb_vm_op_close+0x579/0x960 ? __pfx_hugetlb_vm_op_close+0x10/0x10 remove_vma+0x88/0x130 exit_mmap+0x71e/0xe00 ? __pfx_exit_mmap+0x10/0x10 ? __mutex_unlock_slowpath+0x22e/0x7f0 ? __pfx_exit_aio+0x10/0x10 ? __up_read+0x256/0x690 ? uprobe_clear_state+0x274/0x290 ? mm_update_next_owner+0xa9/0x810 __mmput+0xc9/0x370 exit_mm+0x203/0x2f0 ? __pfx_exit_mm+0x10/0x10 ? taskstats_exit+0x32b/0xa60 do_exit+0x921/0x2740 ? do_raw_spin_lock+0x155/0x3b0 ? __pfx_do_exit+0x10/0x10 ? __pfx_do_raw_spin_lock+0x10/0x10 ? _raw_spin_lock_irq+0xc5/0x100 do_group_exit+0x20c/0x2c0 get_signal+0x168c/0x1720 ? __pfx_get_signal+0x10/0x10 ? schedule+0x165/0x360 arch_do_signal_or_restart+0x8e/0x7d0 ? __pfx_arch_do_signal_or_restart+0x10/0x10 ? __pfx___se_sys_futex+0x10/0x10 syscall_exit_to_user_mode+0xb8/0x2c0 do_syscall_64+0x75/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x422dcd Code: Unable to access opcode bytes at 0x422da3. RSP: 002b:00007ff266cdb208 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007ff266cdbcdc RCX: 0000000000422dcd RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00000000004c7bec RBP: 00007ff266cdb220 R08: 203a6362696c6720 R09: 203a6362696c6720 R10: 0000200000c00000 R11: 0000000000000246 R12: ffffffffffffffd0 R13: 0000000000000002 R14: 00007ffe1cb5f520 R15: 00007ff266cbb000 </TASK> ============================================================ Link: https://lkml.kernel.org/r/20250523-warning_in_page_counter_cancel-v2-1-b6df… Link: https://people.igalia.com/rcn/kernel_logs/20250422__WARNING_in_page_counter… [1] Link: https://lore.kernel.org/all/67000a50.050a0220.49194.048d.GAE@google.com/ [2] Signed-off-by: Ricardo Cañuelo Navarro <rcn(a)igalia.com> Suggested-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Reviewed-by: Liam R. Howlett <Liam.Howlett(a)oracle.com> Cc: Florent Revest <revest(a)google.com> Cc: Jann Horn <jannh(a)google.com> Cc: Oscar Salvador <osalvador(a)suse.de> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 8f3ac832ee7f..4861a7e304bb 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -275,6 +275,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma, bool is_hugetlb_entry_migration(pte_t pte); bool is_hugetlb_entry_hwpoisoned(pte_t pte); void hugetlb_unshare_all_pmds(struct vm_area_struct *vma); +void fixup_hugetlb_reservations(struct vm_area_struct *vma); #else /* !CONFIG_HUGETLB_PAGE */ @@ -468,6 +469,10 @@ static inline vm_fault_t hugetlb_fault(struct mm_struct *mm, static inline void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) { } +static inline void fixup_hugetlb_reservations(struct vm_area_struct *vma) +{ +} + #endif /* !CONFIG_HUGETLB_PAGE */ #ifndef pgd_write diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 55e6796b24d0..6a3cf7935c14 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1250,7 +1250,7 @@ void hugetlb_dup_vma_private(struct vm_area_struct *vma) /* * Reset and decrement one ref on hugepage private reservation. * Called with mm->mmap_lock writer semaphore held. - * This function should be only used by move_vma() and operate on + * This function should be only used by mremap and operate on * same sized vma. It should never come here with last ref on the * reservation. */ @@ -7939,3 +7939,17 @@ void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) hugetlb_unshare_pmds(vma, ALIGN(vma->vm_start, PUD_SIZE), ALIGN_DOWN(vma->vm_end, PUD_SIZE)); } + +/* + * For hugetlb, mremap() is an odd edge case - while the VMA copying is + * performed, we permit both the old and new VMAs to reference the same + * reservation. + * + * We fix this up after the operation succeeds, or if a newly allocated VMA + * is closed as a result of a failure to allocate memory. + */ +void fixup_hugetlb_reservations(struct vm_area_struct *vma) +{ + if (is_vm_hugetlb_page(vma)) + clear_vma_resv_huge_pages(vma); +} diff --git a/mm/mremap.c b/mm/mremap.c index 7db9da609c84..0d4948b720e2 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1188,8 +1188,7 @@ static int copy_vma_and_data(struct vma_remap_struct *vrm, mremap_userfaultfd_prep(new_vma, vrm->uf); } - if (is_vm_hugetlb_page(vma)) - clear_vma_resv_huge_pages(vma); + fixup_hugetlb_reservations(vma); /* Tell pfnmap has moved from this vma */ if (unlikely(vma->vm_flags & VM_PFNMAP)) diff --git a/mm/vma.c b/mm/vma.c index 839d12f02c88..a468d4c29c0c 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -1834,6 +1834,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, return new_vma; out_vma_link: + fixup_hugetlb_reservations(new_vma); vma_close(new_vma); if (new_vma->vm_file)

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FAILED: patch "[PATCH] mm: fix copy_vma() error handling for hugetlb mappings" 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 ee40c9920ac286c5bfe7c811e66ff899266d2582 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025052652-bloated-preoccupy-3ffb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From ee40c9920ac286c5bfe7c811e66ff899266d2582 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ricardo=20Ca=C3=B1uelo=20Navarro?= <rcn(a)igalia.com> Date: Fri, 23 May 2025 14:19:10 +0200 Subject: [PATCH] mm: fix copy_vma() error handling for hugetlb mappings MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit If, during a mremap() operation for a hugetlb-backed memory mapping, copy_vma() fails after the source vma has been duplicated and opened (ie. vma_link() fails), the error is handled by closing the new vma. This updates the hugetlbfs reservation counter of the reservation map which at this point is referenced by both the source vma and the new copy. As a result, once the new vma has been freed and copy_vma() returns, the reservation counter for the source vma will be incorrect. This patch addresses this corner case by clearing the hugetlb private page reservation reference for the new vma and decrementing the reference before closing the vma, so that vma_close() won't update the reservation counter. This is also what copy_vma_and_data() does with the source vma if copy_vma() succeeds, so a helper function has been added to do the fixup in both functions. The issue was reported by a private syzbot instance and can be reproduced using the C reproducer in [1]. It's also a possible duplicate of public syzbot report [2]. The WARNING report is: ============================================================ page_counter underflow: -1024 nr_pages=1024 WARNING: CPU: 0 PID: 3287 at mm/page_counter.c:61 page_counter_cancel+0xf6/0x120 Modules linked in: CPU: 0 UID: 0 PID: 3287 Comm: repro__WARNING_ Not tainted 6.15.0-rc7+ #54 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014 RIP: 0010:page_counter_cancel+0xf6/0x120 Code: ff 5b 41 5e 41 5f 5d c3 cc cc cc cc e8 f3 4f 8f ff c6 05 64 01 27 06 01 48 c7 c7 60 15 f8 85 48 89 de 4c 89 fa e8 2a a7 51 ff <0f> 0b e9 66 ff ff ff 44 89 f9 80 e1 07 38 c1 7c 9d 4c 81 RSP: 0018:ffffc900025df6a0 EFLAGS: 00010246 RAX: 2edfc409ebb44e00 RBX: fffffffffffffc00 RCX: ffff8880155f0000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: dffffc0000000000 R08: ffffffff81c4a23c R09: 1ffff1100330482a R10: dffffc0000000000 R11: ffffed100330482b R12: 0000000000000000 R13: ffff888058a882c0 R14: ffff888058a882c0 R15: 0000000000000400 FS: 0000000000000000(0000) GS:ffff88808fc53000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004b33e0 CR3: 00000000076d6000 CR4: 00000000000006f0 Call Trace: <TASK> page_counter_uncharge+0x33/0x80 hugetlb_cgroup_uncharge_counter+0xcb/0x120 hugetlb_vm_op_close+0x579/0x960 ? __pfx_hugetlb_vm_op_close+0x10/0x10 remove_vma+0x88/0x130 exit_mmap+0x71e/0xe00 ? __pfx_exit_mmap+0x10/0x10 ? __mutex_unlock_slowpath+0x22e/0x7f0 ? __pfx_exit_aio+0x10/0x10 ? __up_read+0x256/0x690 ? uprobe_clear_state+0x274/0x290 ? mm_update_next_owner+0xa9/0x810 __mmput+0xc9/0x370 exit_mm+0x203/0x2f0 ? __pfx_exit_mm+0x10/0x10 ? taskstats_exit+0x32b/0xa60 do_exit+0x921/0x2740 ? do_raw_spin_lock+0x155/0x3b0 ? __pfx_do_exit+0x10/0x10 ? __pfx_do_raw_spin_lock+0x10/0x10 ? _raw_spin_lock_irq+0xc5/0x100 do_group_exit+0x20c/0x2c0 get_signal+0x168c/0x1720 ? __pfx_get_signal+0x10/0x10 ? schedule+0x165/0x360 arch_do_signal_or_restart+0x8e/0x7d0 ? __pfx_arch_do_signal_or_restart+0x10/0x10 ? __pfx___se_sys_futex+0x10/0x10 syscall_exit_to_user_mode+0xb8/0x2c0 do_syscall_64+0x75/0x120 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x422dcd Code: Unable to access opcode bytes at 0x422da3. RSP: 002b:00007ff266cdb208 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: 0000000000000001 RBX: 00007ff266cdbcdc RCX: 0000000000422dcd RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00000000004c7bec RBP: 00007ff266cdb220 R08: 203a6362696c6720 R09: 203a6362696c6720 R10: 0000200000c00000 R11: 0000000000000246 R12: ffffffffffffffd0 R13: 0000000000000002 R14: 00007ffe1cb5f520 R15: 00007ff266cbb000 </TASK> ============================================================ Link: https://lkml.kernel.org/r/20250523-warning_in_page_counter_cancel-v2-1-b6df… Link: https://people.igalia.com/rcn/kernel_logs/20250422__WARNING_in_page_counter… [1] Link: https://lore.kernel.org/all/67000a50.050a0220.49194.048d.GAE@google.com/ [2] Signed-off-by: Ricardo Cañuelo Navarro <rcn(a)igalia.com> Suggested-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Reviewed-by: Liam R. Howlett <Liam.Howlett(a)oracle.com> Cc: Florent Revest <revest(a)google.com> Cc: Jann Horn <jannh(a)google.com> Cc: Oscar Salvador <osalvador(a)suse.de> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 8f3ac832ee7f..4861a7e304bb 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -275,6 +275,7 @@ long hugetlb_change_protection(struct vm_area_struct *vma, bool is_hugetlb_entry_migration(pte_t pte); bool is_hugetlb_entry_hwpoisoned(pte_t pte); void hugetlb_unshare_all_pmds(struct vm_area_struct *vma); +void fixup_hugetlb_reservations(struct vm_area_struct *vma); #else /* !CONFIG_HUGETLB_PAGE */ @@ -468,6 +469,10 @@ static inline vm_fault_t hugetlb_fault(struct mm_struct *mm, static inline void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) { } +static inline void fixup_hugetlb_reservations(struct vm_area_struct *vma) +{ +} + #endif /* !CONFIG_HUGETLB_PAGE */ #ifndef pgd_write diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 55e6796b24d0..6a3cf7935c14 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1250,7 +1250,7 @@ void hugetlb_dup_vma_private(struct vm_area_struct *vma) /* * Reset and decrement one ref on hugepage private reservation. * Called with mm->mmap_lock writer semaphore held. - * This function should be only used by move_vma() and operate on + * This function should be only used by mremap and operate on * same sized vma. It should never come here with last ref on the * reservation. */ @@ -7939,3 +7939,17 @@ void hugetlb_unshare_all_pmds(struct vm_area_struct *vma) hugetlb_unshare_pmds(vma, ALIGN(vma->vm_start, PUD_SIZE), ALIGN_DOWN(vma->vm_end, PUD_SIZE)); } + +/* + * For hugetlb, mremap() is an odd edge case - while the VMA copying is + * performed, we permit both the old and new VMAs to reference the same + * reservation. + * + * We fix this up after the operation succeeds, or if a newly allocated VMA + * is closed as a result of a failure to allocate memory. + */ +void fixup_hugetlb_reservations(struct vm_area_struct *vma) +{ + if (is_vm_hugetlb_page(vma)) + clear_vma_resv_huge_pages(vma); +} diff --git a/mm/mremap.c b/mm/mremap.c index 7db9da609c84..0d4948b720e2 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1188,8 +1188,7 @@ static int copy_vma_and_data(struct vma_remap_struct *vrm, mremap_userfaultfd_prep(new_vma, vrm->uf); } - if (is_vm_hugetlb_page(vma)) - clear_vma_resv_huge_pages(vma); + fixup_hugetlb_reservations(vma); /* Tell pfnmap has moved from this vma */ if (unlikely(vma->vm_flags & VM_PFNMAP)) diff --git a/mm/vma.c b/mm/vma.c index 839d12f02c88..a468d4c29c0c 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -1834,6 +1834,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, return new_vma; out_vma_link: + fixup_hugetlb_reservations(new_vma); vma_close(new_vma); if (new_vma->vm_file)

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