Messages in this thread | | | Date | Wed, 28 Feb 2018 18:50:09 -0800 | From | Jaegeuk Kim <> | Subject | Re: [PATCH v4] Revert "f2fs crypto: avoid unneeded memory allocation in ->readdir" |
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On 02/28, Chao Yu wrote: > Hi Jaegeuk, > > On 2018/2/28 13:48, Jaegeuk Kim wrote: > > Hi Yunlong, > > > > As Eric pointed out, how do you think using nohighmem for directory likewise > > I'd like to ask, at the beginning, why we choose to use highmem for dentry page? > any history reason there?
There was no huge preference on it based on performance. I just wanted not to abuse lowmem.
Thanks,
> > > ext4, which looks like more efficient? Actually, we don't need to do this in > > most of recent kernels, right? > > It's OK to me to keep a line with ext4. > > Thanks, > > > > > Thanks, > > > > On 02/28, Yunlong Song wrote: > >> This reverts commit e06f86e61d7a67fe6e826010f57aa39c674f4b1b. > >> > >> Conflicts: > >> fs/f2fs/dir.c > >> > >> In some platforms (such as arm), high memory is used, then the > >> decrypting filename will cause panic, the reason see commit > >> 569cf1876a32e574ba8a7fb825cd91bafd003882 ("f2fs crypto: allocate buffer > >> for decrypting filename"): > >> > >> We got dentry pages from high_mem, and its address space directly goes into the > >> decryption path via f2fs_fname_disk_to_usr. > >> But, sg_init_one assumes the address is not from high_mem, so we can get this > >> panic since it doesn't call kmap_high but kunmap_high is triggered at the end. > >> > >> kernel BUG at ../../../../../../kernel/mm/highmem.c:290! > >> Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM > >> ... > >> (kunmap_high+0xb0/0xb8) from [<c0114534>] (__kunmap_atomic+0xa0/0xa4) > >> (__kunmap_atomic+0xa0/0xa4) from [<c035f028>] (blkcipher_walk_done+0x128/0x1ec) > >> (blkcipher_walk_done+0x128/0x1ec) from [<c0366c24>] (crypto_cbc_decrypt+0xc0/0x170) > >> (crypto_cbc_decrypt+0xc0/0x170) from [<c0367148>] (crypto_cts_decrypt+0xc0/0x114) > >> (crypto_cts_decrypt+0xc0/0x114) from [<c035ea98>] (async_decrypt+0x40/0x48) > >> (async_decrypt+0x40/0x48) from [<c032ca34>] (f2fs_fname_disk_to_usr+0x124/0x304) > >> (f2fs_fname_disk_to_usr+0x124/0x304) from [<c03056fc>] (f2fs_fill_dentries+0xac/0x188) > >> (f2fs_fill_dentries+0xac/0x188) from [<c03059c8>] (f2fs_readdir+0x1f0/0x300) > >> (f2fs_readdir+0x1f0/0x300) from [<c0218054>] (vfs_readdir+0x90/0xb4) > >> (vfs_readdir+0x90/0xb4) from [<c0218418>] (SyS_getdents64+0x64/0xcc) > >> (SyS_getdents64+0x64/0xcc) from [<c0105ba0>] (ret_fast_syscall+0x0/0x30) > >> > >> Howerver, later patch: > >> commit e06f86e61d7a ("f2fs crypto: avoid unneeded memory allocation in ->readdir") > >> reverts the codes, which causes panic again in arm, so fix it back to the old version. > >> > >> Signed-off-by: Yunlong Song <yunlong.song@huawei.com> > >> Reviewed-by: Chao Yu <yuchao0@huawei.com> > >> --- > >> fs/f2fs/dir.c | 7 +++++++ > >> 1 file changed, 7 insertions(+) > >> > >> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c > >> index f00b5ed..de2e295 100644 > >> --- a/fs/f2fs/dir.c > >> +++ b/fs/f2fs/dir.c > >> @@ -825,9 +825,16 @@ int f2fs_fill_dentries(struct dir_context *ctx, struct f2fs_dentry_ptr *d, > >> int save_len = fstr->len; > >> int err; > >> > >> + de_name.name = f2fs_kmalloc(sbi, de_name.len, GFP_NOFS); > >> + if (!de_name.name) > >> + return -ENOMEM; > >> + > >> + memcpy(de_name.name, d->filename[bit_pos], de_name.len); > >> + > >> err = fscrypt_fname_disk_to_usr(d->inode, > >> (u32)de->hash_code, 0, > >> &de_name, fstr); > >> + kfree(de_name.name); > >> if (err) > >> return err; > >> > >> -- > >> 1.8.5.2 > > > > . > >
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