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Message-ID: <202509030347.6cUT1zxe-lkp@intel.com>
Date: Wed, 3 Sep 2025 03:56:54 +0800
From: kernel test robot <lkp@...el.com>
To: YangWen <anmuxixixi@...il.com>, hirofumi@...l.parknet.co.jp
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
YangWen <anmuxixixi@...il.com>
Subject: Re: [PATCH] fat: fix data-race between fat12_ent_put() and
fat_mirror_bhs()
Hi YangWen,
kernel test robot noticed the following build errors:
[auto build test ERROR on brauner-vfs/vfs.all]
[also build test ERROR on linus/master v6.17-rc4 next-20250902]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/YangWen/fat-fix-data-race-between-fat12_ent_put-and-fat_mirror_bhs/20250902-162253
base: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.all
patch link: https://lore.kernel.org/r/20250902081727.7146-1-anmuxixixi%40gmail.com
patch subject: [PATCH] fat: fix data-race between fat12_ent_put() and fat_mirror_bhs()
config: csky-randconfig-002-20250903 (https://download.01.org/0day-ci/archive/20250903/202509030347.6cUT1zxe-lkp@intel.com/config)
compiler: csky-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250903/202509030347.6cUT1zxe-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202509030347.6cUT1zxe-lkp@intel.com/
All errors (new ones prefixed by >>):
fs/fat/fatent.c: In function 'fat_mirror_bhs':
>> fs/fat/fatent.c:382:25: error: called object 'is_fat12' is not a function or function pointer
382 | bool is_fat12 = is_fat12(sbi);
| ^~~~~~~~
fs/fat/fatent.c:382:14: note: declared here
382 | bool is_fat12 = is_fat12(sbi);
| ^~~~~~~~
vim +/is_fat12 +382 fs/fat/fatent.c
374
375 /* FIXME: We can write the blocks as more big chunk. */
376 static int fat_mirror_bhs(struct super_block *sb, struct buffer_head **bhs,
377 int nr_bhs)
378 {
379 struct msdos_sb_info *sbi = MSDOS_SB(sb);
380 struct buffer_head *c_bh;
381 int err, n, copy;
> 382 bool is_fat12 = is_fat12(sbi);
383
384 err = 0;
385 for (copy = 1; copy < sbi->fats; copy++) {
386 sector_t backup_fat = sbi->fat_length * copy;
387
388 for (n = 0; n < nr_bhs; n++) {
389 c_bh = sb_getblk(sb, backup_fat + bhs[n]->b_blocknr);
390 if (!c_bh) {
391 err = -ENOMEM;
392 goto error;
393 }
394 /* Avoid race with userspace read via bdev */
395 lock_buffer(c_bh);
396 /*
397 * For FAT12, protect memcpy() of the source sector
398 * against concurrent 12-bit entry updates in
399 * fat12_ent_put(), otherwise we may copy a torn
400 * pair of bytes into the mirror FAT.
401 */
402 if (is_fat12)
403 spin_lock(&fat12_entry_lock);
404 memcpy(c_bh->b_data, bhs[n]->b_data, sb->s_blocksize);
405 if (is_fat12)
406 spin_unlock(&fat12_entry_lock);
407 set_buffer_uptodate(c_bh);
408 unlock_buffer(c_bh);
409 mark_buffer_dirty_inode(c_bh, sbi->fat_inode);
410 if (sb->s_flags & SB_SYNCHRONOUS)
411 err = sync_dirty_buffer(c_bh);
412 brelse(c_bh);
413 if (err)
414 goto error;
415 }
416 }
417 error:
418 return err;
419 }
420
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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