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Subject[REGRESSION] "Locked" and "Pss" in /proc/*/smaps are the same
Date
While looking around in /proc on my v4.14.52 system I noticed that
all processes got a lot of "Locked" memory in /proc/*/smaps. A lot
more memory than a regular user can usually lock with mlock().

commit 493b0e9d945fa9dfe96be93ae41b4ca4b6fdb317 (v4.14-rc1) seems
to have changed the behavior of "Locked".

commit 493b0e9d945fa9dfe96be93ae41b4ca4b6fdb317
Author: Daniel Colascione <dancol@google.com>
Date: Wed Sep 6 16:25:08 2017 -0700

mm: add /proc/pid/smaps_rollup

Before that commit the code was like this. Notice the VM_LOCKED
check.

seq_printf(m,
"Size: %8lu kB\n"
"Rss: %8lu kB\n"
"Pss: %8lu kB\n"
"Shared_Clean: %8lu kB\n"
"Shared_Dirty: %8lu kB\n"
"Private_Clean: %8lu kB\n"
"Private_Dirty: %8lu kB\n"
"Referenced: %8lu kB\n"
"Anonymous: %8lu kB\n"
"LazyFree: %8lu kB\n"
"AnonHugePages: %8lu kB\n"
"ShmemPmdMapped: %8lu kB\n"
"Shared_Hugetlb: %8lu kB\n"
"Private_Hugetlb: %7lu kB\n"
"Swap: %8lu kB\n"
"SwapPss: %8lu kB\n"
"KernelPageSize: %8lu kB\n"
"MMUPageSize: %8lu kB\n"
"Locked: %8lu kB\n",
(vma->vm_end - vma->vm_start) >> 10,
mss.resident >> 10,
(unsigned long)(mss.pss >> (10 + PSS_SHIFT)),
mss.shared_clean >> 10,
mss.shared_dirty >> 10,
mss.private_clean >> 10,
mss.private_dirty >> 10,
mss.referenced >> 10,
mss.anonymous >> 10,
mss.lazyfree >> 10,
mss.anonymous_thp >> 10,
mss.shmem_thp >> 10,
mss.shared_hugetlb >> 10,
mss.private_hugetlb >> 10,
mss.swap >> 10,
(unsigned long)(mss.swap_pss >> (10 + PSS_SHIFT)),
vma_kernel_pagesize(vma) >> 10,
vma_mmu_pagesize(vma) >> 10,
(vma->vm_flags & VM_LOCKED) ?
(unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);

After that commit Locked is now the same as Pss. This looks like a
mistake.

seq_printf(m,
"Rss: %8lu kB\n"
"Pss: %8lu kB\n"
"Shared_Clean: %8lu kB\n"
"Shared_Dirty: %8lu kB\n"
"Private_Clean: %8lu kB\n"
"Private_Dirty: %8lu kB\n"
"Referenced: %8lu kB\n"
"Anonymous: %8lu kB\n"
"LazyFree: %8lu kB\n"
"AnonHugePages: %8lu kB\n"
"ShmemPmdMapped: %8lu kB\n"
"Shared_Hugetlb: %8lu kB\n"
"Private_Hugetlb: %7lu kB\n"
"Swap: %8lu kB\n"
"SwapPss: %8lu kB\n"
"Locked: %8lu kB\n",
mss->resident >> 10,
(unsigned long)(mss->pss >> (10 + PSS_SHIFT)),
mss->shared_clean >> 10,
mss->shared_dirty >> 10,
mss->private_clean >> 10,
mss->private_dirty >> 10,
mss->referenced >> 10,
mss->anonymous >> 10,
mss->lazyfree >> 10,
mss->anonymous_thp >> 10,
mss->shmem_thp >> 10,
mss->shared_hugetlb >> 10,
mss->private_hugetlb >> 10,
mss->swap >> 10,
(unsigned long)(mss->swap_pss >> (10 + PSS_SHIFT)),
(unsigned long)(mss->pss >> (10 + PSS_SHIFT)));

The latest git has changed a bit but the functionality is the
same.

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