> From: Chao Yu <c...@kernel.org>
> Sent: Thursday, March 27, 2025 3:02 PM
> To: Yohan Joung <jyh...@gmail.com>; jaeg...@kernel.org; daeh...@gmail.com
> Cc: c...@kernel.org; linux-f2fs-devel@lists.sourceforge.net; linux-
> ker...@vger.kernel.org; 정요한(JOUNG YOHAN) Mobile AE <yohan.jo...@sk.com>
> Subject: [External Mail] Re: [PATCH] f2fs: prevent the current section
> from being selected as a victim during garbage collection
>
> On 3/26/25 22:14, Yohan Joung wrote:
> > When selecting a victim using next_victim_seg in a large section, the
> > selected section might already have been cleared and designated as the
> > new current section, making it actively in use.
> > This behavior causes inconsistency between the SIT and SSA.
>
> Hi, does this fix your issue?
This is an issue that arises when dividing
a large section into segments for garbage collection.
caused by the background GC (garbage collection) thread in large section
f2fs_gc(victim_section) -> f2fs_clear_prefree_segments(victim_section)->
cursec(victim_section) -> f2fs_gc(victim_section by next_victim_seg)
Because the call stack is different,
I think that in order to handle everything at once,
we need to address it within do_garbage_collect,
or otherwise include it on both sides. What do you think?
[30146.337471][ T1300] F2FS-fs (dm-54): Inconsistent segment (70961) type [0,
1] in SSA and SIT
[30146.346151][ T1300] Call trace:
[30146.346152][ T1300] dump_backtrace+0xe8/0x10c
[30146.346157][ T1300] show_stack+0x18/0x28
[30146.346158][ T1300] dump_stack_lvl+0x50/0x6c
[30146.346161][ T1300] dump_stack+0x18/0x28
[30146.346162][ T1300] f2fs_stop_checkpoint+0x1c/0x3c
[30146.346165][ T1300] do_garbage_collect+0x41c/0x271c
[30146.346167][ T1300] f2fs_gc+0x27c/0x828
[30146.346168][ T1300] gc_thread_func+0x290/0x88c
[30146.346169][ T1300] kthread+0x11c/0x164
[30146.346172][ T1300] ret_from_fork+0x10/0x20
struct curseg_info : 0xffffff803f95e800 {
segno : 0x11531 : 70961
}
struct f2fs_sb_info : 0xffffff8811d12000 {
next_victim_seg[0] : 0x11531 : 70961
}
>
> https://lore.kernel.org/linux-f2fs-devel/20250325080646.3291947-2-
> c...@kernel.org
>
> Thanks,
>
> >
> > Signed-off-by: Yohan Joung <yohan.jo...@sk.com>
> > ---
> > fs/f2fs/gc.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c index
> > 2b8f9239bede..4b5d18e395eb 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -1926,6 +1926,10 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct
> f2fs_gc_control *gc_control)
> > goto stop;
> > }
> >
> > + if (__is_large_section(sbi) &&
> > + IS_CURSEC(sbi, GET_SEC_FROM_SEG(sbi, segno)))
> > + goto stop;
> > +
> > seg_freed = do_garbage_collect(sbi, segno, &gc_list, gc_type,
> > gc_control->should_migrate_blocks,
> > gc_control->one_time);
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