On Mon, Jul 31, 2023 at 05:36:36PM +0800, Shiyang Ruan wrote: > > > 在 2023/7/29 23:15, Darrick J. Wong 写道: > > On Thu, Jun 29, 2023 at 04:16:51PM +0800, Shiyang Ruan wrote: > > > This patch is inspired by Dan's "mm, dax, pmem: Introduce > > > dev_pagemap_failure()"[1]. With the help of dax_holder and > > > ->notify_failure() mechanism, the pmem driver is able to ask filesystem > > > on it to unmap all files in use, and notify processes who are using > > > those files. > > > > > > Call trace: > > > trigger unbind > > > -> unbind_store() > > > -> ... (skip) > > > -> devres_release_all() > > > -> kill_dax() > > > -> dax_holder_notify_failure(dax_dev, 0, U64_MAX, MF_MEM_PRE_REMOVE) > > > -> xfs_dax_notify_failure() > > > `-> freeze_super() // freeze (kernel call) > > > `-> do xfs rmap > > > ` -> mf_dax_kill_procs() > > > ` -> collect_procs_fsdax() // all associated processes > > > ` -> unmap_and_kill() > > > ` -> invalidate_inode_pages2_range() // drop file's cache > > > `-> thaw_super() // thaw (both kernel & user call) > > > > > > Introduce MF_MEM_PRE_REMOVE to let filesystem know this is a remove > > > event. Use the exclusive freeze/thaw[2] to lock the filesystem to prevent > > > new dax mapping from being created. Do not shutdown filesystem directly > > > if configuration is not supported, or if failure range includes metadata > > > area. Make sure all files and processes(not only the current progress) > > > are handled correctly. Also drop the cache of associated files before > > > pmem is removed. > > > > > > [1]: https://lore.kernel.org/linux-mm/161604050314.1463742.14151665140035795571.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > > [2]: https://lore.kernel.org/linux-xfs/168688010689.860947.1788875898367401950.stgit@frogsfrogsfrogs/ > > > > > > Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx> > > > --- > > > drivers/dax/super.c | 3 +- > > > fs/xfs/xfs_notify_failure.c | 86 ++++++++++++++++++++++++++++++++++--- > > > include/linux/mm.h | 1 + > > > mm/memory-failure.c | 17 ++++++-- > > > 4 files changed, 96 insertions(+), 11 deletions(-) > > > > > > diff --git a/drivers/dax/super.c b/drivers/dax/super.c > > > index c4c4728a36e4..2e1a35e82fce 100644 > > > --- a/drivers/dax/super.c > > > +++ b/drivers/dax/super.c > > > @@ -323,7 +323,8 @@ void kill_dax(struct dax_device *dax_dev) > > > return; > > > if (dax_dev->holder_data != NULL) > > > - dax_holder_notify_failure(dax_dev, 0, U64_MAX, 0); > > > + dax_holder_notify_failure(dax_dev, 0, U64_MAX, > > > + MF_MEM_PRE_REMOVE); > > > clear_bit(DAXDEV_ALIVE, &dax_dev->flags); > > > synchronize_srcu(&dax_srcu); > > > diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c > > > index 4a9bbd3fe120..f6ec56b76db6 100644 > > > --- a/fs/xfs/xfs_notify_failure.c > > > +++ b/fs/xfs/xfs_notify_failure.c > > > @@ -22,6 +22,7 @@ > > > #include <linux/mm.h> > > > #include <linux/dax.h> > > > +#include <linux/fs.h> > > > struct xfs_failure_info { > > > xfs_agblock_t startblock; > > > @@ -73,10 +74,16 @@ xfs_dax_failure_fn( > > > struct xfs_mount *mp = cur->bc_mp; > > > struct xfs_inode *ip; > > > struct xfs_failure_info *notify = data; > > > + struct address_space *mapping; > > > + pgoff_t pgoff; > > > + unsigned long pgcnt; > > > int error = 0; > > > if (XFS_RMAP_NON_INODE_OWNER(rec->rm_owner) || > > > (rec->rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK))) { > > > + /* Continue the query because this isn't a failure. */ > > > + if (notify->mf_flags & MF_MEM_PRE_REMOVE) > > > + return 0; > > > notify->want_shutdown = true; > > > return 0; > > > } > > > @@ -92,14 +99,55 @@ xfs_dax_failure_fn( > > > return 0; > > > } > > > - error = mf_dax_kill_procs(VFS_I(ip)->i_mapping, > > > - xfs_failure_pgoff(mp, rec, notify), > > > - xfs_failure_pgcnt(mp, rec, notify), > > > - notify->mf_flags); > > > + mapping = VFS_I(ip)->i_mapping; > > > + pgoff = xfs_failure_pgoff(mp, rec, notify); > > > + pgcnt = xfs_failure_pgcnt(mp, rec, notify); > > > + > > > + /* Continue the rmap query if the inode isn't a dax file. */ > > > + if (dax_mapping(mapping)) > > > + error = mf_dax_kill_procs(mapping, pgoff, pgcnt, > > > + notify->mf_flags); > > > + > > > + /* Invalidate the cache in dax pages. */ > > > + if (notify->mf_flags & MF_MEM_PRE_REMOVE) > > > + invalidate_inode_pages2_range(mapping, pgoff, > > > + pgoff + pgcnt - 1); > > > + > > > xfs_irele(ip); > > > return error; > > > } > > > +static void > > > +xfs_dax_notify_failure_freeze( > > > + struct xfs_mount *mp) > > > +{ > > > + struct super_block *sb = mp->m_super; > > > > Nit: extra space right ^ here. > > > > > + > > > + /* Wait until no one is holding the FREEZE_HOLDER_KERNEL. */ > > > + while (freeze_super(sb, FREEZE_HOLDER_KERNEL) != 0) { > > > + // Shall we just wait, or print warning then return -EBUSY? > > > > Hm. PRE_REMOVE gets called before the pmem gets unplugged, right? So > > we'll send a second notification after it goes away, right? > > For the first question, yes. > > But I'm not sure about the second one. Do you mean: we'll send this > notification again if unbind didn't success because freeze_super() returns > -EBUSY? In other words, if the previous unbind operation did not work, we > could unbind the device again. Yeah. If the MF_MEM_PRE_REMOVE fails with EBUSY, then call it again without PRE_REMOVE and let it kill processes. --D > > > > If so, then I'd say return the error here instead of looping, and live > > with a kernel-frozen fs discarding the PRE_REMOVE message. > > > > > + delay(HZ / 10); > > > + } > > > +} > > > + > > > +static void > > > +xfs_dax_notify_failure_thaw( > > > + struct xfs_mount *mp) > > > +{ > > > + struct super_block *sb = mp->m_super; > > > + int error; > > > + > > > + error = thaw_super(sb, FREEZE_HOLDER_KERNEL); > > > + if (error) > > > + xfs_emerg(mp, "still frozen after notify failure, err=%d", > > > + error); > > > + /* > > > + * Also thaw userspace call anyway because the device is about to be > > > + * removed immediately. > > > + */ > > > + thaw_super(sb, FREEZE_HOLDER_USERSPACE); > > > +} > > > + > > > static int > > > xfs_dax_notify_ddev_failure( > > > struct xfs_mount *mp, > > > @@ -120,7 +168,7 @@ xfs_dax_notify_ddev_failure( > > > error = xfs_trans_alloc_empty(mp, &tp); > > > if (error) > > > - return error; > > > + goto out; > > > for (; agno <= end_agno; agno++) { > > > struct xfs_rmap_irec ri_low = { }; > > > @@ -165,11 +213,23 @@ xfs_dax_notify_ddev_failure( > > > } > > > xfs_trans_cancel(tp); > > > + > > > + /* > > > + * Determine how to shutdown the filesystem according to the > > > + * error code and flags. > > > + */ > > > if (error || notify.want_shutdown) { > > > xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_ONDISK); > > > if (!error) > > > error = -EFSCORRUPTED; > > > - } > > > + } else if (mf_flags & MF_MEM_PRE_REMOVE) > > > + xfs_force_shutdown(mp, SHUTDOWN_FORCE_UMOUNT); > > > + > > > +out: > > > + /* Thaw the fs if it is freezed before. */ > > > + if (mf_flags & MF_MEM_PRE_REMOVE) > > > + xfs_dax_notify_failure_thaw(mp); > > > > _thaw should be called from the same function that called _freeze. > > Will fix this. > > > > > The rest of the patch seems ok to me. > > Thank you! > > > -- > Ruan. > > > > > --D > > > > > + > > > return error; > > > } > > > @@ -197,6 +257,8 @@ xfs_dax_notify_failure( > > > if (mp->m_logdev_targp && mp->m_logdev_targp->bt_daxdev == dax_dev && > > > mp->m_logdev_targp != mp->m_ddev_targp) { > > > + if (mf_flags & MF_MEM_PRE_REMOVE) > > > + return 0; > > > xfs_err(mp, "ondisk log corrupt, shutting down fs!"); > > > xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_ONDISK); > > > return -EFSCORRUPTED; > > > @@ -210,6 +272,12 @@ xfs_dax_notify_failure( > > > ddev_start = mp->m_ddev_targp->bt_dax_part_off; > > > ddev_end = ddev_start + bdev_nr_bytes(mp->m_ddev_targp->bt_bdev) - 1; > > > + /* Notify failure on the whole device. */ > > > + if (offset == 0 && len == U64_MAX) { > > > + offset = ddev_start; > > > + len = bdev_nr_bytes(mp->m_ddev_targp->bt_bdev); > > > + } > > > + > > > /* Ignore the range out of filesystem area */ > > > if (offset + len - 1 < ddev_start) > > > return -ENXIO; > > > @@ -226,6 +294,12 @@ xfs_dax_notify_failure( > > > if (offset + len - 1 > ddev_end) > > > len = ddev_end - offset + 1; > > > + if (mf_flags & MF_MEM_PRE_REMOVE) { > > > + xfs_info(mp, "device is about to be removed!"); > > > + /* Freeze fs to prevent new mappings from being created. */ > > > + xfs_dax_notify_failure_freeze(mp); > > > + } > > > + > > > return xfs_dax_notify_ddev_failure(mp, BTOBB(offset), BTOBB(len), > > > mf_flags); > > > } > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > > index 27ce77080c79..a80c255b88d2 100644 > > > --- a/include/linux/mm.h > > > +++ b/include/linux/mm.h > > > @@ -3576,6 +3576,7 @@ enum mf_flags { > > > MF_UNPOISON = 1 << 4, > > > MF_SW_SIMULATED = 1 << 5, > > > MF_NO_RETRY = 1 << 6, > > > + MF_MEM_PRE_REMOVE = 1 << 7, > > > }; > > > int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, > > > unsigned long count, int mf_flags); > > > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > > > index 5b663eca1f29..483b75f2fcfb 100644 > > > --- a/mm/memory-failure.c > > > +++ b/mm/memory-failure.c > > > @@ -688,7 +688,7 @@ static void add_to_kill_fsdax(struct task_struct *tsk, struct page *p, > > > */ > > > static void collect_procs_fsdax(struct page *page, > > > struct address_space *mapping, pgoff_t pgoff, > > > - struct list_head *to_kill) > > > + struct list_head *to_kill, bool pre_remove) > > > { > > > struct vm_area_struct *vma; > > > struct task_struct *tsk; > > > @@ -696,8 +696,15 @@ static void collect_procs_fsdax(struct page *page, > > > i_mmap_lock_read(mapping); > > > read_lock(&tasklist_lock); > > > for_each_process(tsk) { > > > - struct task_struct *t = task_early_kill(tsk, true); > > > + struct task_struct *t = tsk; > > > + /* > > > + * Search for all tasks while MF_MEM_PRE_REMOVE, because the > > > + * current may not be the one accessing the fsdax page. > > > + * Otherwise, search for the current task. > > > + */ > > > + if (!pre_remove) > > > + t = task_early_kill(tsk, true); > > > if (!t) > > > continue; > > > vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { > > > @@ -1793,6 +1800,7 @@ int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, > > > dax_entry_t cookie; > > > struct page *page; > > > size_t end = index + count; > > > + bool pre_remove = mf_flags & MF_MEM_PRE_REMOVE; > > > mf_flags |= MF_ACTION_REQUIRED | MF_MUST_KILL; > > > @@ -1804,9 +1812,10 @@ int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index, > > > if (!page) > > > goto unlock; > > > - SetPageHWPoison(page); > > > + if (!pre_remove) > > > + SetPageHWPoison(page); > > > - collect_procs_fsdax(page, mapping, index, &to_kill); > > > + collect_procs_fsdax(page, mapping, index, &to_kill, pre_remove); > > > unmap_and_kill(&to_kill, page_to_pfn(page), mapping, > > > index, mf_flags); > > > unlock: > > > -- > > > 2.40.1 > > >
