From: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: djwong@kernel.org, brauner@kernel.org, david@fromorbit.com,
chandan.babu@oracle.com, akpm@linux-foundation.org,
linux-fsdevel@vger.kernel.org, hare@suse.de,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-xfs@vger.kernel.org, mcgrof@kernel.org,
gost.dev@samsung.com, p.raghav@samsung.com
Subject: Re: [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement
Date: Fri, 26 Apr 2024 15:49:19 +0000 [thread overview]
Message-ID: <20240426154919.hupoxurihhbfj67x@quentin> (raw)
In-Reply-To: <Ziq4qAJ_p7P9Smpn@casper.infradead.org>
On Thu, Apr 25, 2024 at 09:10:16PM +0100, Matthew Wilcox wrote:
> On Thu, Apr 25, 2024 at 01:37:40PM +0200, Pankaj Raghav (Samsung) wrote:
> > From: Pankaj Raghav <p.raghav@samsung.com>
> >
> > Splitting a larger folio with a base order is supported using
> > split_huge_page_to_list_to_order() API. However, using that API for LBS
> > is resulting in an NULL ptr dereference error in the writeback path [1].
> >
> > Refuse to split a folio if it has minimum folio order requirement until
> > we can start using split_huge_page_to_list_to_order() API. Splitting the
> > folio can be added as a later optimization.
> >
> > [1] https://gist.github.com/mcgrof/d12f586ec6ebe32b2472b5d634c397df
>
> Obviously this has to be tracked down and fixed before this patchset can
> be merged ... I think I have some ideas. Let me look a bit. How
> would I go about reproducing this?
I am able to reproduce it in a VM with 4G RAM and running generic/447
(sometimes you have to run it twice) on a 16K BS on a 4K PS system.
I have a suspicion on this series: https://lore.kernel.org/linux-fsdevel/20240215063649.2164017-1-hch@lst.de/
but I am still unsure why this is happening when we split with LBS
configurations.
If you have kdevops installed, then go with Luis's suggestion, or else
this is my local config.
This is the diff I applied instead of this patch:
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 9859aa4f7553..63ee7b6ed03d 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3041,6 +3041,10 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
{
struct folio *folio = page_folio(page);
struct deferred_split *ds_queue = get_deferred_split_queue(folio);
+ unsigned int mapping_min_order = mapping_min_folio_order(folio->mapping);
+
+ if (!folio_test_anon(folio))
+ new_order = max_t(unsigned int, mapping_min_order, new_order);
/* reset xarray order to new order after split */
XA_STATE_ORDER(xas, &folio->mapping->i_pages, folio->index, new_order);
struct anon_vma *anon_vma = NULL;
@@ -3117,6 +3121,8 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
goto out;
}
+ // XXX: Remove it later
+ VM_WARN_ON_FOLIO((new_order < mapping_min_order), folio);
gfp = current_gfp_context(mapping_gfp_mask(mapping) &
GFP_RECLAIM_MASK);
(END)
xfstests is based on https://github.com/kdave/xfstests/tree/v2024.04.14
xfstests config:
[default]
FSTYP=xfs
RESULT_BASE=/root/results/
DUMP_CORRUPT_FS=1
CANON_DEVS=yes
RECREATE_TEST_DEV=true
TEST_DEV=/dev/nvme0n1
TEST_DIR=/media/test
SCRATCH_DEV=/dev/vdb
SCRATCH_MNT=/media/scratch
LOGWRITES_DEV=/dev/vdc
[16k_4ks]
MKFS_OPTIONS='-f -m reflink=1,rmapbt=1, -i sparse=1, -b size=16k, -s size=4k'
[nix-shell:~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
vdb 254:16 0 32G 0 disk /media/scratch
vdc 254:32 0 32G 0 disk
nvme0n1 259:0 0 32G 0 disk /media/test
$ ./check -s 16k_4ks generic/447
BT:
[ 74.170698] BUG: KASAN: null-ptr-deref in filemap_get_folios_tag+0x14b/0x510
[ 74.170938] Write of size 4 at addr 0000000000000036 by task kworker/u16:6/284
[ 74.170938]
[ 74.170938] CPU: 0 PID: 284 Comm: kworker/u16:6 Not tainted 6.9.0-rc4-00011-g4676d00b6f6f #7
[ 74.170938] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
[ 74.170938] Workqueue: writeback wb_workfn (flush-254:16)
[ 74.170938] Call Trace:
[ 74.170938] <TASK>
[ 74.170938] dump_stack_lvl+0x51/0x70
[ 74.170938] kasan_report+0xab/0xe0
[ 74.170938] ? filemap_get_folios_tag+0x14b/0x510
[ 74.170938] kasan_check_range+0x35/0x1b0
[ 74.170938] filemap_get_folios_tag+0x14b/0x510
[ 74.170938] ? __pfx_filemap_get_folios_tag+0x10/0x10
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] writeback_iter+0x508/0xcc0
[ 74.170938] ? __pfx_iomap_do_writepage+0x10/0x10
[ 74.170938] write_cache_pages+0x80/0x100
[ 74.170938] ? __pfx_write_cache_pages+0x10/0x10
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? _raw_spin_lock+0x87/0xe0
[ 74.170938] iomap_writepages+0x85/0xe0
[ 74.170938] xfs_vm_writepages+0xe3/0x140 [xfs]
[ 74.170938] ? __pfx_xfs_vm_writepages+0x10/0x10 [xfs]
[ 74.170938] ? kasan_save_track+0x10/0x30
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? __kasan_kmalloc+0x7b/0x90
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? virtqueue_add_split+0x605/0x1b00
[ 74.170938] do_writepages+0x176/0x740
[ 74.170938] ? __pfx_do_writepages+0x10/0x10
[ 74.170938] ? __pfx_virtqueue_add_split+0x10/0x10
[ 74.170938] ? __pfx_update_sd_lb_stats.constprop.0+0x10/0x10
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? virtqueue_add_sgs+0xfe/0x130
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? virtblk_add_req+0x15c/0x280
[ 74.170938] __writeback_single_inode+0x9f/0x840
[ 74.170938] ? wbc_attach_and_unlock_inode+0x345/0x5d0
[ 74.170938] writeback_sb_inodes+0x491/0xce0
[ 74.170938] ? __pfx_wb_calc_thresh+0x10/0x10
[ 74.170938] ? __pfx_writeback_sb_inodes+0x10/0x10
[ 74.170938] ? __wb_calc_thresh+0x1a0/0x3c0
[ 74.170938] ? __pfx_down_read_trylock+0x10/0x10
[ 74.170938] ? wb_over_bg_thresh+0x16b/0x5e0
[ 74.170938] ? __pfx_move_expired_inodes+0x10/0x10
[ 74.170938] __writeback_inodes_wb+0xb7/0x200
[ 74.170938] wb_writeback+0x2c4/0x660
[ 74.170938] ? __pfx_wb_writeback+0x10/0x10
[ 74.170938] ? __pfx__raw_spin_lock_irq+0x10/0x10
[ 74.170938] wb_workfn+0x54e/0xaf0
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? __pfx_wb_workfn+0x10/0x10
[ 74.170938] ? __pfx___schedule+0x10/0x10
[ 74.170938] ? __pfx__raw_spin_lock_irq+0x10/0x10
[ 74.170938] process_one_work+0x622/0x1020
[ 74.170938] worker_thread+0x844/0x10e0
[ 74.170938] ? srso_return_thunk+0x5/0x5f
[ 74.170938] ? __kthread_parkme+0x82/0x150
[ 74.170938] ? __pfx_worker_thread+0x10/0x10
[ 74.170938] kthread+0x2b4/0x380
[ 74.170938] ? __pfx_kthread+0x10/0x10
[ 74.170938] ret_from_fork+0x30/0x70
[ 74.170938] ? __pfx_kthread+0x10/0x10
[ 74.170938] ret_from_fork_asm+0x1a/0x30
[ 74.170938] </TASK>
next prev parent reply other threads:[~2024-04-26 15:49 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-25 11:37 [PATCH v4 00/11] enable bs > ps in XFS Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 01/11] readahead: rework loop in page_cache_ra_unbounded() Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 02/11] fs: Allow fine-grained control of folio sizes Pankaj Raghav (Samsung)
2024-04-25 18:07 ` Hannes Reinecke
2024-04-26 15:09 ` Darrick J. Wong
2024-04-25 11:37 ` [PATCH v4 03/11] filemap: allocate mapping_min_order folios in the page cache Pankaj Raghav (Samsung)
2024-04-25 19:04 ` Hannes Reinecke
2024-04-26 15:12 ` Darrick J. Wong
2024-04-28 20:59 ` Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 04/11] readahead: allocate folios with mapping_min_order in readahead Pankaj Raghav (Samsung)
2024-04-25 18:53 ` Matthew Wilcox
2024-04-25 11:37 ` [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement Pankaj Raghav (Samsung)
2024-04-25 20:10 ` Matthew Wilcox
2024-04-26 0:47 ` Luis Chamberlain
2024-04-26 23:46 ` Luis Chamberlain
2024-04-28 0:57 ` Luis Chamberlain
2024-04-29 3:56 ` Luis Chamberlain
2024-04-29 14:29 ` Zi Yan
2024-04-30 0:31 ` Luis Chamberlain
2024-04-30 0:49 ` Luis Chamberlain
2024-04-30 2:43 ` Zi Yan
2024-04-30 19:27 ` Luis Chamberlain
2024-05-01 4:13 ` Matthew Wilcox
2024-05-01 14:28 ` Matthew Wilcox
2024-04-26 15:49 ` Pankaj Raghav (Samsung) [this message]
2024-04-25 11:37 ` [PATCH v4 06/11] filemap: cap PTE range to be created to i_size in folio_map_range() Pankaj Raghav (Samsung)
2024-04-25 20:24 ` Matthew Wilcox
2024-04-26 12:54 ` Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size Pankaj Raghav (Samsung)
2024-04-26 6:22 ` Christoph Hellwig
2024-04-26 11:43 ` Pankaj Raghav (Samsung)
2024-04-27 5:12 ` Christoph Hellwig
2024-04-29 21:02 ` Pankaj Raghav (Samsung)
2024-04-27 3:26 ` Matthew Wilcox
2024-04-27 4:52 ` Christoph Hellwig
2024-04-25 11:37 ` [PATCH v4 08/11] xfs: use kvmalloc for xattr buffers Pankaj Raghav (Samsung)
2024-04-26 15:18 ` Darrick J. Wong
2024-04-28 21:06 ` Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 09/11] xfs: expose block size in stat Pankaj Raghav (Samsung)
2024-04-26 15:15 ` Darrick J. Wong
2024-04-25 11:37 ` [PATCH v4 10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count() Pankaj Raghav (Samsung)
2024-04-26 15:16 ` Darrick J. Wong
2024-04-25 11:37 ` [PATCH v4 11/11] xfs: enable block size larger than page size support Pankaj Raghav (Samsung)
2024-04-26 15:18 ` Darrick J. Wong
2024-04-27 4:42 ` [PATCH v4 00/11] enable bs > ps in XFS Ritesh Harjani
2024-04-27 5:05 ` Darrick J. Wong
2024-04-29 20:39 ` Pankaj Raghav (Samsung)
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