[bug report] shmem: prepare huge= mount option and sysfs knob

[bug report] shmem: prepare huge= mount option and sysfs knob

[Dan Carpenter]

Hello Kirill A. Shutemov,

The patch 5a6e75f8110c: "shmem: prepare huge= mount option and sysfs
knob" from Jul 26, 2016, leads to the following static checker
warning:

	mm/shmem.c:4013 shmem_init()
	warn: assigning (-2) to unsigned variable 'SHMEM_SB(shm_mnt->mnt_sb)->huge'

mm/shmem.c
  4012  #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
  4013          if (has_transparent_hugepage() && shmem_huge < SHMEM_HUGE_DENY)
  4014                  SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;


SHMEM_HUGE_DENY is -1 so the value less than that is SHMEM_HUGE_FORCE (-2).

  4015          else
  4016                  shmem_huge = 0; /* just in case it was patched */
  4017  #endif
  4018          return 0;

Btw, if shmem_parse_huge() returns SHMEM_HUGE_FORCE, then both callers
treat that as an error.  The handling for SHMEM_HUGE_FORCE is confusing
for my tiny brain.

regards,
dan carpenter

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