[LU-7465] False positive memory leak in sanity tests due to iov_iter_get_pages_alloc

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.8.0
• Affects Version/s: Lustre 2.8.0
• Labels: patch
• Environment: 3.16 and later kernels
• Severity: 3
• Assignee: WC Triage
• Reporter: Wally Wang (Inactive)

Description

The iov_iter_get_pages_alloc function(introduced by 3.16 kernels, LU-6260) is a kernel function which does not use Lustre's hook to keep track of memory allocation and therefore the number of bytes tallied by Lustre's ll_free_user_pages() appeared to be 'extra'. This happens only to direct io read and it is not a real leak of memory. It can be reproduced by a number of sanity tests, such as 205, to result in the message similar to:

25243:0:(class_obd.c:646:cleanup_obdclass()) obd_memory max:
18446744073709549568, leaked: 18446744073709549568

Issue Links

• is related to: LU-7052 iovec created with iov_iter_get_pages_alloc must be freed with kvfree