From: Chao Yu <c...@kernel.org>
> Sent: 07 March 2023 15:14
>
> 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 there is __packed attribute in struct rb_entry, but there
> is no __packed attribute in struct victim_entry, so wrong offset of key
> field will be parsed in struct rb_entry in f2fs_check_rb_tree_consistence,
> it describes memory layouts of struct rb_entry and struct victim_entry in
> 32-bits platform as below:
>
> struct rb_entry {
> [0] struct rb_node rb_node;
> union {
> struct {...};
> [12] unsigned long long key;
> } __packed;
This __packed removes the 4-byte pad before the union.
I bet it should be removed...
> }
> size of struct rb_entry: 20
>
> struct victim_entry {
> [0] struct rb_node rb_node;
> union {
> struct {...};
> [16] struct victim_info vi;
> };
> [32] struct list_head list;
> }
> size of struct victim_entry: 40
>
> This patch tries to add __packed attribute in below structure:
> - discard_info, discard_cmd
> - extent_info, extent_node
> - victim_info, victim_entry
> in order to fix this unaligned field offset issue in 32-bits platform.
Have you looked at the amount of extra code that gets generated
on systems that fault misaligned accesses?
Plausibly adding __packed __aligned(4) will restrict the compiler
to just aligning 64bit items on 32bit boundaries.
But even then is you pass the address of a misaligned structure
to another function it will fault later of.
You haven't actually said where the misalignment comes from.
If the code is doing (foo *)(ptr + 1) then that is broken
when the alignments of 'ptr' and 'foo' differ.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT,
UK
Registration No: 1397386 (Wales)
_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
