| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <67f0669d-1063-486f-a995-f8d18634a1be@redhat.com>
Date: Tue, 22 Apr 2025 17:23:51 +0200
From: David Hildenbrand <david@...hat.com>
To: Shivank Garg <shivankg@....com>, shaggy@...nel.org,
akpm@...ux-foundation.org
Cc: willy@...radead.org, wangkefeng.wang@...wei.com, jane.chu@...cle.com,
ziy@...dia.com, donettom@...ux.ibm.com, apopple@...dia.com,
jfs-discussion@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, syzbot+8bb6fd945af4e0ad9299@...kaller.appspotmail.com
Subject: Re: [PATCH V4 2/2] jfs: implement migrate_folio for jfs_metapage_aops
On 22.04.25 13:40, Shivank Garg wrote:
> Add the missing migrate_folio operation to jfs_metapage_aops to fix
> warnings during memory compaction. These warnings were introduced by
> commit 7ee3647243e5 ("migrate: Remove call to ->writepage") which
> added explicit warnings when filesystems don't implement migrate_folio.
>
> System reports following warnings:
> jfs_metapage_aops does not implement migrate_folio
> WARNING: CPU: 0 PID: 6870 at mm/migrate.c:955 fallback_migrate_folio mm/migrate.c:953 [inline]
> WARNING: CPU: 0 PID: 6870 at mm/migrate.c:955 move_to_new_folio+0x70e/0x840 mm/migrate.c:1007
>
> Implement metapage_migrate_folio which handles both single and multiple
> metapages per page configurations.
>
> Fixes: 35474d52c605 ("jfs: Convert metapage_writepage to metapage_write_folio")
> Reported-by: syzbot+8bb6fd945af4e0ad9299@...kaller.appspotmail.com
> Closes: https://lore.kernel.org/all/67faff52.050a0220.379d84.001b.GAE@google.com
> Signed-off-by: Shivank Garg <shivankg@....com>
> ---
> fs/jfs/jfs_metapage.c | 94 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 94 insertions(+)
>
> diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
> index df575a873ec6..a12fbd92cc69 100644
> --- a/fs/jfs/jfs_metapage.c
> +++ b/fs/jfs/jfs_metapage.c
> @@ -15,6 +15,7 @@
> #include <linux/mempool.h>
> #include <linux/seq_file.h>
> #include <linux/writeback.h>
> +#include <linux/migrate.h>
> #include "jfs_incore.h"
> #include "jfs_superblock.h"
> #include "jfs_filsys.h"
> @@ -151,6 +152,54 @@ static inline void dec_io(struct folio *folio, blk_status_t status,
> handler(folio, anchor->status);
> }
>
> +static int __metapage_migrate_folio(struct address_space *mapping, struct folio *dst,
> + struct folio *src, enum migrate_mode mode)
> +{
> + struct meta_anchor *src_anchor = src->private;
> + struct metapage *mps[MPS_PER_PAGE] = {0};
> + struct metapage *mp;
> + int i, rc;
> +
> + for (i = 0; i < MPS_PER_PAGE; i++) {
> + mp = src_anchor->mp[i];
> + if (mp && metapage_locked(mp))
> + return -EAGAIN;
> + }
> +
> + rc = filemap_migrate_folio(mapping, dst, src, mode);
> + if (rc != MIGRATEPAGE_SUCCESS)
> + return rc;
> +
> + for (i = 0; i < MPS_PER_PAGE; i++) {
> + mp = src_anchor->mp[i];
> + if (!mp)
> + continue;
> + if (unlikely(insert_metapage(dst, mp))) {
> + /* If error, roll-back previosly inserted pages */
> + for (int j = 0 ; j < i; j++) {
> + if (mps[j])
> + remove_metapage(dst, mps[j]);
> + }
> + return -EAGAIN;
> + }
> + mps[i] = mp;
> + }
> +
> + /* Update the metapage and remove it from src */
> + for (i = 0; i < MPS_PER_PAGE; i++) {
> + mp = mps[i];
> + if (mp) {
> + int page_offset = mp->data - folio_address(src);
> +
> + mp->data = folio_address(dst) + page_offset;
> + mp->folio = dst;
> + remove_metapage(src, mp);
> + }
> + }
> +
> + return MIGRATEPAGE_SUCCESS;
> +}
> +
> #else
> static inline struct metapage *folio_to_mp(struct folio *folio, int offset)
> {
> @@ -175,6 +224,32 @@ static inline void remove_metapage(struct folio *folio, struct metapage *mp)
> #define inc_io(folio) do {} while(0)
> #define dec_io(folio, status, handler) handler(folio, status)
>
> +static int __metapage_migrate_folio(struct address_space *mapping, struct folio *dst,
> + struct folio *src, enum migrate_mode mode)
> +{
> + struct metapage *mp;
> + int page_offset;
> + int rc;
> +
> + mp = folio_to_mp(src, 0);
> + if (mp && metapage_locked(mp))
> + return -EAGAIN;
> +
> + rc = filemap_migrate_folio(mapping, dst, src, mode);
> + if (rc != MIGRATEPAGE_SUCCESS)
> + return rc;
> +
> + if (unlikely(insert_metapage(dst, mp)))
> + return -EAGAIN;
> +
> + page_offset = mp->data - folio_address(src);
> + mp->data = folio_address(dst) + page_offset;
> + mp->folio = dst;
> + remove_metapage(src, mp);
> +
> + return MIGRATEPAGE_SUCCESS;
> +}
> +
> #endif
>
> static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
> @@ -554,6 +629,24 @@ static bool metapage_release_folio(struct folio *folio, gfp_t gfp_mask)
> return ret;
> }
>
> +/**
> + * metapage_migrate_folio - Migration function for JFS metapages
> + */
> +static int metapage_migrate_folio(struct address_space *mapping, struct folio *dst,
> + struct folio *src, enum migrate_mode mode)
> +{
> + int expected_count;
> +
> + if (!src->private)
> + return filemap_migrate_folio(mapping, dst, src, mode);
> +
> + /* Check whether page does not have extra refs before we do more work */
> + expected_count = folio_migration_expected_refs(mapping, src);
> + if (folio_ref_count(src) != expected_count)
Probably no need for the temporary variable.
Hm, makes me wonder if it should be called
folio_migration_expected_ref_count() ... :)
Bit it's even longer, whatever you think is best.
--
Cheers,
David / dhildenb
Powered by blists - more mailing lists