Doug / smarc-fsl-linux-kernel

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Commit ad820c5dd47dff9397ef1e94388bc6577983f68b

Authored by Nick Piggin
Committed by Linus Torvalds
1 parent 5ddfae16bd
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[PATCH] smaps: shared fix 

The point of the smaps "shared" is to count the number of pages that are
mapped by more than one process, according to Mauricio Lin.  However, smaps
uses page_count for this, so it will return a false positive for every page
that is mapped by just that one process, which is also in pagecache or
swapcache.  There are false positive situations for anonymous pages not in
swapcache as well: - page reclaim, migration - get_user_pages (eg.
direct-io, ptrace)

Use page_mapcount instead, to count the number of mappings to the page.

Use vm_normal_page so that weird things like /dev/mem aren't counted either.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Showing 1 changed file with 4 additions and 5 deletions Side-by-side Diff

... ... @@ -204,7 +204,6 @@
204 204 {
205 205 pte_t *pte, ptent;
206 206 spinlock_t *ptl;
207   - unsigned long pfn;
208 207 struct page *page;
209 208  
210 209 pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
211 210  
... ... @@ -214,12 +213,12 @@
214 213 continue;
215 214  
216 215 mss->resident += PAGE_SIZE;
217   - pfn = pte_pfn(ptent);
218   - if (!pfn_valid(pfn))
  216 +
  217 + page = vm_normal_page(vma, addr, ptent);
  218 + if (!page)
219 219 continue;
220 220  
221   - page = pfn_to_page(pfn);
222   - if (page_count(page) >= 2) {
  221 + if (page_mapcount(page) >= 2) {
223 222 if (pte_dirty(ptent))
224 223 mss->shared_dirty += PAGE_SIZE;
225 224 else