Hi Jeff,
I checked the code, found one suspicious place as below:
- f2fs_build_node_manager
- init_node_manager
- __get_nat_bitmaps
- disable_nat_bits(, true)
disable_nat_bits(.., lock)
{
...
if (lock)
spin_lock_irqsave(&sbi->cp_lock, flags);
__clear_ckpt_flags(F2FS_CKPT(sbi), CP_NAT_BITS_FLAG);
kvfree(NM_I(sbi)->nat_bits);
NM_I(sbi)->nat_bits = NULL;
if (lock)
spin_unlock_irqrestore(&sbi->cp_lock, flags);
}
I don't think we have to call kvfree() under spinlock, so I can simply change it
as below to fix the warning.
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 19e5a5f..e7c99b5 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1667,6 +1667,7 @@ static inline void clear_ckpt_flags(struct f2fs_sb_info
*sbi, unsigned int f)
static inline void disable_nat_bits(struct f2fs_sb_info *sbi, bool lock)
{
unsigned long flags;
+ unsigned char *nat_bits;
/*
* In order to re-enable nat_bits we need to call fsck.f2fs by
@@ -1677,10 +1678,12 @@ static inline void disable_nat_bits(struct f2fs_sb_info
*sbi, bool lock)
if (lock)
spin_lock_irqsave(&sbi->cp_lock, flags);
__clear_ckpt_flags(F2FS_CKPT(sbi), CP_NAT_BITS_FLAG);
- kvfree(NM_I(sbi)->nat_bits);
+ nat_bits = NM_I(sbi)->nat_bits;
NM_I(sbi)->nat_bits = NULL;
if (lock)
spin_unlock_irqrestore(&sbi->cp_lock, flags);
+
+ kvfree(nat_bits);
}
BTW, in f2fs, it's possible to hit kvfree()->vfree() in the case of we face
memory pressure, due to f2fs_kmalloc() will fallback to call kvmalloc() once
failed in kmalloc().
Thanks,
On 2019/7/25 20:37, Jeff Layton wrote:
> I was playing with a patch to add a might_sleep_if(!in_interrupt()); to
> the top of kvfree:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux.git/commit/?h=mm-5.4&id=e49f335dedc18a2ee0ac7791134b282abd9c857f
>
> The kernel test robot picked it up and saw a new warning pop in a f2fs
> call stack. I took a quick look but didn't see the bug, but one of you
> guys may want to play with that patch and try to hunt it down.
>
> Cheers,
>
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