lkml.org 
[lkml]   [2022]   [Nov]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH] f2fs: fix atgc bug on issue in 32bits platform
From
On 2022/11/7 13:04, Zhiguo Niu wrote:
> Dear Chao
>
> Chao Yu <chao@kernel.org <mailto:chao@kernel.org>> 于2022年11月7日周一 09:25写道:
>
> On 2022/11/4 15:40, zhiguo.niu wrote:
> > From: Zhiguo Niu <zhiguo.niu@unisoc.com <mailto:zhiguo.niu@unisoc.com>>
> >
> > There is bug on issue after atgc feature is enabled in
> > 32bits platform as the following log:
> >
> > F2FS-fs (dm-x): inconsistent rbtree, cur(3470333575168) next(3320009719808)
> > ------------[ cut here ]------------
> > kernel BUG at fs/f2fs/gc.c:602!
> > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM
> > PC is at get_victim_by_default+0x13c0/0x1498
> > LR is at f2fs_check_rb_tree_consistence+0xc4/0xd4
> > ....
> > [<c04d98b0>] (get_victim_by_default) from [<c04d4f44>] (f2fs_gc+0x220/0x6cc)
> > [<c04d4f44>] (f2fs_gc) from [<c04d4780>] (gc_thread_func+0x2ac/0x708)
> > [<c04d4780>] (gc_thread_func) from [<c015c774>] (kthread+0x1a8/0x1b4)
> > [<c015c774>] (kthread) from [<c01010b4>] (ret_from_fork+0x14/0x20)
> >
> > The reason is the 64bits key in struct rb_entry has __packed attibute
> > but has not in struct victim_entry, so the wrong key value got by
> > in f2fs_check_rb_tree_consistence, the following are the memory layouts
> > of struct rb_entry and struct victim_entry in 32bits platform:
> >
> > struct rb_entry {
> >     [0] struct rb_node rb_node;
> >         union {
> >             struct {...};
> >    [12]     unsigned long long key;
> >         };
> > }
> > struct victim_entry {
> >     [0] struct rb_node rb_node;
> >         union {
> >             struct {...};
> >    [16]     struct victim_info vi;
> >         };
> >    [32] struct list_head list;
> > }
>
> Shouldn't we add __packed for struct victim_entry?
>
>  I try to keep it consistent with struct rb_entry (__packed is only added to union for 64bits key),
> victim_entry.vi.mtime is used to store the key, and rb_entry.key is used to verify the key,
> so make sure that the memory offsets of the 64 bits key in these two structures are the same.
> Other members of victim_entry, such as list, i think there is no problem because of it storaged and loaded
> are both based on struct victim_entry

I'm not sure, there will be any further update in struct rb_node and
struct list_head later, so, IMO, it will be more safe to add __packed to
align all fields in structure to byte.

Thanks,

>
> >
> > This patch fix this inconsistence layout of 64bits key between
> > struct rb_entry and struct victim_entry.
> >
>
> Fixes: 093749e296e2 ("f2fs: support age threshold based garbage collection")
>
> > Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com <mailto:zhiguo.niu@unisoc.com>>
>

\
 
 \ /
  Last update: 2022-11-07 15:51    [W:0.706 / U:0.424 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site