linux-kernel - [PATCH] proc: do not show VmExe bigger than total executable virtual memory

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Date:   Fri, 06 Oct 2017 14:32:34 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] proc: do not show VmExe bigger than total executable
 virtual memory

If start_code / end_code pointers are screwed then "VmExe" could be bigger
than total executable virtual memory and "VmLib" becomes negative:

VmExe:	  294320 kB
VmLib:	18446744073709327564 kB

VmExe and VmLib documented as text segment and shared library code size.

Now their sum will be always equal to mm->exec_vm which sums size of
executable and not writable and not stack areas.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
---
 fs/proc/task_mmu.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 5589b4bd4b85..d3819beb2d30 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -46,8 +46,11 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
 	if (hiwater_rss < mm->hiwater_rss)
 		hiwater_rss = mm->hiwater_rss;
 
-	text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK)) >> 10;
-	lib = (mm->exec_vm << (PAGE_SHIFT-10)) - text;
+	/* split executable areas between text and lib */
+	text = PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK);
+	text = min(text, mm->exec_vm << PAGE_SHIFT);
+	lib = (mm->exec_vm << PAGE_SHIFT) - text;
+
 	swap = get_mm_counter(mm, MM_SWAPENTS);
 	ptes = PTRS_PER_PTE * sizeof(pte_t) * atomic_long_read(&mm->nr_ptes);
 	pmds = PTRS_PER_PMD * sizeof(pmd_t) * mm_nr_pmds(mm);
@@ -78,7 +81,9 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
 		file << (PAGE_SHIFT-10),
 		shmem << (PAGE_SHIFT-10),
 		mm->data_vm << (PAGE_SHIFT-10),
-		mm->stack_vm << (PAGE_SHIFT-10), text, lib,
+		mm->stack_vm << (PAGE_SHIFT-10),
+		text >> 10,
+		lib >> 10,
 		ptes >> 10,
 		pmds >> 10,
 		swap << (PAGE_SHIFT-10));