This is a note to let you know that I've just added the patch titled xfs: use current->journal_info for detecting transaction recursion to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xfs-use-current-journal_info-for-detecting-transaction-recursion.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Mon Jul 4 04:42:02 PM CEST 2022 From: Amir Goldstein <amir73il@xxxxxxxxx> Date: Sun, 3 Jul 2022 08:04:50 +0300 Subject: xfs: use current->journal_info for detecting transaction recursion To: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx>, "Darrick J . Wong" <djwong@xxxxxxxxxx>, Leah Rumancik <leah.rumancik@xxxxxxxxx>, Chandan Babu R <chandan.babu@xxxxxxxxxx>, Luis Chamberlain <mcgrof@xxxxxxxxxx>, Adam Manzanares <a.manzanares@xxxxxxxxxxx>, linux-xfs@xxxxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx, Dave Chinner <dchinner@xxxxxxxxxx>, Christoph Hellwig <hch@xxxxxx> Message-ID: <20220703050456.3222610-2-amir73il@xxxxxxxxx> From: Dave Chinner <dchinner@xxxxxxxxxx> commit 756b1c343333a5aefcc26b0409f3fd16f72281bf upstream. Because the iomap code using PF_MEMALLOC_NOFS to detect transaction recursion in XFS is just wrong. Remove it from the iomap code and replace it with XFS specific internal checks using current->journal_info instead. [djwong: This change also realigns the lifetime of NOFS flag changes to match the incore transaction, instead of the inconsistent scheme we have now.] Fixes: 9070733b4efa ("xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS") Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/iomap/buffered-io.c | 7 ------- fs/xfs/libxfs/xfs_btree.c | 12 ++++++++++-- fs/xfs/xfs_aops.c | 17 +++++++++++++++-- fs/xfs/xfs_trans.c | 20 +++++--------------- fs/xfs/xfs_trans.h | 30 ++++++++++++++++++++++++++++++ 5 files changed, 60 insertions(+), 26 deletions(-) --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1461,13 +1461,6 @@ iomap_do_writepage(struct page *page, st goto redirty; /* - * Given that we do not allow direct reclaim to call us, we should - * never be called in a recursive filesystem reclaim context. - */ - if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) - goto redirty; - - /* * Is this page beyond the end of the file? * * The page index is less than the end_index, adjust the end_offset --- a/fs/xfs/libxfs/xfs_btree.c +++ b/fs/xfs/libxfs/xfs_btree.c @@ -2811,7 +2811,7 @@ xfs_btree_split_worker( struct xfs_btree_split_args *args = container_of(work, struct xfs_btree_split_args, work); unsigned long pflags; - unsigned long new_pflags = PF_MEMALLOC_NOFS; + unsigned long new_pflags = 0; /* * we are in a transaction context here, but may also be doing work @@ -2823,12 +2823,20 @@ xfs_btree_split_worker( new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; current_set_flags_nested(&pflags, new_pflags); + xfs_trans_set_context(args->cur->bc_tp); args->result = __xfs_btree_split(args->cur, args->level, args->ptrp, args->key, args->curp, args->stat); - complete(args->done); + xfs_trans_clear_context(args->cur->bc_tp); current_restore_flags_nested(&pflags, new_pflags); + + /* + * Do not access args after complete() has run here. We don't own args + * and the owner may run and free args before we return here. + */ + complete(args->done); + } /* --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -62,7 +62,7 @@ xfs_setfilesize_trans_alloc( * We hand off the transaction to the completion thread now, so * clear the flag here. */ - current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); + xfs_trans_clear_context(tp); return 0; } @@ -125,7 +125,7 @@ xfs_setfilesize_ioend( * thus we need to mark ourselves as being in a transaction manually. * Similarly for freeze protection. */ - current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); + xfs_trans_set_context(tp); __sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS); /* we abort the update if there was an IO error */ @@ -577,6 +577,12 @@ xfs_vm_writepage( { struct xfs_writepage_ctx wpc = { }; + if (WARN_ON_ONCE(current->journal_info)) { + redirty_page_for_writepage(wbc, page); + unlock_page(page); + return 0; + } + return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops); } @@ -587,6 +593,13 @@ xfs_vm_writepages( { struct xfs_writepage_ctx wpc = { }; + /* + * Writing back data in a transaction context can result in recursive + * transactions. This is bad, so issue a warning and get out of here. + */ + if (WARN_ON_ONCE(current->journal_info)) + return 0; + xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops); } --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -68,6 +68,7 @@ xfs_trans_free( xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false); trace_xfs_trans_free(tp, _RET_IP_); + xfs_trans_clear_context(tp); if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT)) sb_end_intwrite(tp->t_mountp->m_super); xfs_trans_free_dqinfo(tp); @@ -119,7 +120,8 @@ xfs_trans_dup( ntp->t_rtx_res = tp->t_rtx_res - tp->t_rtx_res_used; tp->t_rtx_res = tp->t_rtx_res_used; - ntp->t_pflags = tp->t_pflags; + + xfs_trans_switch_context(tp, ntp); /* move deferred ops over to the new tp */ xfs_defer_move(ntp, tp); @@ -153,9 +155,6 @@ xfs_trans_reserve( int error = 0; bool rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0; - /* Mark this thread as being in a transaction */ - current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); - /* * Attempt to reserve the needed disk blocks by decrementing * the number needed from the number available. This will @@ -163,10 +162,8 @@ xfs_trans_reserve( */ if (blocks > 0) { error = xfs_mod_fdblocks(mp, -((int64_t)blocks), rsvd); - if (error != 0) { - current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); + if (error != 0) return -ENOSPC; - } tp->t_blk_res += blocks; } @@ -240,9 +237,6 @@ undo_blocks: xfs_mod_fdblocks(mp, (int64_t)blocks, rsvd); tp->t_blk_res = 0; } - - current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); - return error; } @@ -266,6 +260,7 @@ xfs_trans_alloc( tp = kmem_cache_zalloc(xfs_trans_zone, GFP_KERNEL | __GFP_NOFAIL); if (!(flags & XFS_TRANS_NO_WRITECOUNT)) sb_start_intwrite(mp->m_super); + xfs_trans_set_context(tp); /* * Zero-reservation ("empty") transactions can't modify anything, so @@ -878,7 +873,6 @@ __xfs_trans_commit( xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); - current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); xfs_trans_free(tp); /* @@ -910,7 +904,6 @@ out_unreserve: xfs_log_ticket_ungrant(mp->m_log, tp->t_ticket); tp->t_ticket = NULL; } - current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); xfs_trans_free_items(tp, !!error); xfs_trans_free(tp); @@ -970,9 +963,6 @@ xfs_trans_cancel( tp->t_ticket = NULL; } - /* mark this thread as no longer being in a transaction */ - current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS); - xfs_trans_free_items(tp, dirty); xfs_trans_free(tp); } --- a/fs/xfs/xfs_trans.h +++ b/fs/xfs/xfs_trans.h @@ -268,4 +268,34 @@ xfs_trans_item_relog( return lip->li_ops->iop_relog(lip, tp); } +static inline void +xfs_trans_set_context( + struct xfs_trans *tp) +{ + ASSERT(current->journal_info == NULL); + tp->t_pflags = memalloc_nofs_save(); + current->journal_info = tp; +} + +static inline void +xfs_trans_clear_context( + struct xfs_trans *tp) +{ + if (current->journal_info == tp) { + memalloc_nofs_restore(tp->t_pflags); + current->journal_info = NULL; + } +} + +static inline void +xfs_trans_switch_context( + struct xfs_trans *old_tp, + struct xfs_trans *new_tp) +{ + ASSERT(current->journal_info == old_tp); + new_tp->t_pflags = old_tp->t_pflags; + old_tp->t_pflags = 0; + current->journal_info = new_tp; +} + #endif /* __XFS_TRANS_H__ */ Patches currently in stable-queue which might be from amir73il@xxxxxxxxx are queue-5.10/xfs-rename-variable-mp-to-parsing_mp.patch queue-5.10/xfs-fix-xfs_trans-slab-cache-name.patch queue-5.10/xfs-skip-repetitive-warnings-about-mount-options.patch queue-5.10/xfs-use-current-journal_info-for-detecting-transaction-recursion.patch queue-5.10/xfs-update-superblock-counters-correctly-for-lazysbcount.patch queue-5.10/xfs-ensure-xfs_errortag_random_default-matches-xfs_errtag_max.patch queue-5.10/xfs-fix-xfs_reflink_unshare-usage-of-filemap_write_and_wait_range.patch