lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Tue, 18 Aug 2020 18:01:33 +0800 From: Chao Yu <yuchao0@...wei.com> To: Sahitya Tummala <stummala@...eaurora.org> CC: Jaegeuk Kim <jaegeuk@...nel.org>, <linux-f2fs-devel@...ts.sourceforge.net>, <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] f2fs: fix indefinite loop scanning for free nid On 2020/8/18 17:55, Sahitya Tummala wrote: > On Tue, Aug 18, 2020 at 04:29:05PM +0800, Chao Yu wrote: >> On 2020/8/14 16:05, Sahitya Tummala wrote: >>> If the sbi->ckpt->next_free_nid is not NAT block aligned and if there >>> are free nids in that NAT block between the start of the block and >>> next_free_nid, then those free nids will not be scanned in scan_nat_page(). >>> This results into mismatch between nm_i->available_nids and the sum of >>> nm_i->free_nid_count of all NAT blocks scanned. And nm_i->available_nids >>> will always be greater than the sum of free nids in all the blocks. >>> Under this condition, if we use all the currently scanned free nids, >>> then it will loop forever in f2fs_alloc_nid() as nm_i->available_nids >>> is still not zero but nm_i->free_nid_count of that partially scanned >>> NAT block is zero. >>> >>> Fix this to align the nm_i->next_scan_nid to the first nid of the >>> corresponding NAT block. >>> >>> Signed-off-by: Sahitya Tummala <stummala@...eaurora.org> >>> --- >>> fs/f2fs/node.c | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c >>> index 9bbaa26..d615e59 100644 >>> --- a/fs/f2fs/node.c >>> +++ b/fs/f2fs/node.c >>> @@ -2402,6 +2402,8 @@ static int __f2fs_build_free_nids(struct f2fs_sb_info *sbi, >>> if (IS_ERR(page)) { >>> ret = PTR_ERR(page); >>> } else { >>> + if (nid % NAT_ENTRY_PER_BLOCK) >>> + nid = NAT_BLOCK_OFFSET(nid) * NAT_ENTRY_PER_BLOCK; >> >> How about moving this logic to the beginning of __f2fs_build_free_nids(), >> after nid reset? >> > > Sure, I will move it. > >> BTW, it looks we can add unlikely in this judgment condition? > > But it may not be an unlikely as it can happen whenever checkpoint is done, > based on the next available free nid in function next_free_nid(), which can happen > quite a few times, right? Oh, yes, I missed that place, please ignore that suggestion.. :) Thanks, > > Hitting the loop forever issue condition due to this could be a rare/difficult to > reproduce but this check itself may not be unlikely in my opinion. > > Thanks, > >> >> Thanks, >> >>> ret = scan_nat_page(sbi, page, nid); >>> f2fs_put_page(page, 1); >>> } >>> >
Powered by blists - more mailing lists