I bisected kernels/merges between 5.3 and 5.4-rc1 in master (torvalds) Commit with timestamp 19 Sep 2019 00:35:20 (UTC) is first kernel with s2disk hibernation snapshotting failing: e6bc9de714972cac34daa1dc1567ee48a47a9342 Merge tag 'vfs-5.4-merge-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux Commit with timestamp 19 Sep 2019 00:33:32 (UTC) is the last kernel where s2disk is working properly : b6c0d35772468173b5d3a7f6162079611e68a1e8 Merge tag 'ovl-fixes-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs Obviously commit dc617f29dbe5ef0c8ced65ce62c464af1daaab3d from Darrick J. Wong<darrick.wong@oracle.com> from 20 Aug 2019 14:55:16 UTC is causing the problem. Darrick,please fix your commit or revert your commit for 5.4.22 as it is going to cause many problems for laptop users once the ubuntu is released next month (apr 2020) with 5.4 kernel and with long term support. Hibernation is essential feature for laptops. I suggest you make exception for s2disk to allow it to write to swap devices. Adjust the feature such that when kernel in grub has parameters: resume=/dev/nvme0n1p8 snapshot_gid=4 then any user in group snapshot_gid will be allowed to write only to swap device specified by resume kernel parameter. All other writings to swap device are disallowed.
See also https://bugs.launchpad.net/ubuntu/+source/linux-5.4/+bug/1864930
I only add. Many hibernation facilities (systemd,pm-hibernate,hibernate) rely on s2disk so it is very important s2disk is working.
patch on top of commit e6bc9de714972cac34daa1dc1567ee48a47a9342 marian@kubuntu2004:~/kernelubuntu/linux$ git diff diff --git a/include/linux/swap.h b/include/linux/swap.h index de2c67a33b7e..da1dc5a338cc 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -456,6 +456,7 @@ extern void swap_free(swp_entry_t); extern void swapcache_free_entries(swp_entry_t *entries, int n); extern int free_swap_and_cache(swp_entry_t); extern int swap_type_of(dev_t, sector_t, struct block_device **); +extern void swap_relockall(void); extern unsigned int count_swap_pages(int, int); extern sector_t map_swap_page(struct page *, struct block_device **); extern sector_t swapdev_block(int, pgoff_t); diff --git a/kernel/power/user.c b/kernel/power/user.c index 77438954cc2b..bfef2097edaa 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -271,6 +271,8 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, break; } error = hibernation_restore(data->platform_support); + if (!error) + swap_relockall(); break; case SNAPSHOT_FREE: @@ -372,10 +374,16 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, */ swdev = new_decode_dev(swap_area.dev); if (swdev) { + struct block_device *bd; offset = swap_area.offset; - data->swap = swap_type_of(swdev, offset, NULL); + data->swap = swap_type_of(swdev, offset, &bd); if (data->swap < 0) error = -ENODEV; + + inode_lock(bd->bd_inode); + bd->bd_inode->i_flags &= ~S_SWAPFILE; + inode_unlock(bd->bd_inode); + bdput(bd); } else { data->swap = -1; error = -EINVAL; diff --git a/mm/swapfile.c b/mm/swapfile.c index dab43523afdd..c7c83d3a313b 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1799,6 +1799,32 @@ int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) return -ENODEV; } +/* Re-lock swap devices after resuming from userspace suspend. */ +void swap_relockall(void) +{ + int type; + + spin_lock(&swap_lock); + for (type = 0; type < nr_swapfiles; type++) { + struct swap_info_struct *sis = swap_info[type]; + struct block_device *bdev = bdgrab(sis->bdev); + + /* + * uswsusp only knows how to suspend to block devices, so we + * can skip swap files. + */ + if (!(sis->flags & SWP_WRITEOK) || + !(sis->flags & SWP_BLKDEV)) + continue; + + inode_lock(bdev->bd_inode); + bdev->bd_inode->i_flags |= S_SWAPFILE; + inode_unlock(bdev->bd_inode); + bdput(bdev); + } + spin_unlock(&swap_lock); +} + /* * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev * corresponding to given index in swap_info (swap type).
this patch applies well to version/tag 5.4 too and to head/master (as of 29 Feb 2020 6:40 am UTC)
Created attachment 287719 [details] Hibernation s2disk swap device wrate protection Consult darrick.wong@oracle.com I do it on his behalf.
Comment from Darrick: This patch should make it so that uswsusp can unlock the swap device prior to writing the memory image to disk, and then lock it again when resuming.
patch in attachment applies cleanly to 5.4.23 marian@kubuntu2004:~$ wget -q https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.23.tar.xz marian@kubuntu2004:~$ tar xf linux-5.4.23.tar.xz marian@kubuntu2004:~$ cd linux-5.4.23/ marian@kubuntu2004:~/linux-5.4.23$ wget -q -O hibernate.patch https://bugzilla.kernel.org/attachment.cgi?id=287719 marian@kubuntu2004:~/linux-5.4.23$ patch -p1 < hibernate.patch patching file include/linux/swap.h patching file kernel/power/user.c patching file mm/swapfile.c