Eric Lee / smarc-fsl-linux-kernel

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Commit 2919bfd0758257c469abef8c26c3e516bbebb851

Authored by Hugh Dickins
Committed by Linus Torvalds
1 parent 73ae31e598
Exists in master and in 39 other branches 8mp-imx_5.4.70_2.3.0, 8qm-imx_5.4.70_2.3.0, emb_imx_lf-5.15.y, emb_lf-6.1.y, 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, imx_4.1.15_1.0.0_ga, pitx_8mp_lf-5.10.y, rt-smarc-imx_4.1.15_1.0.0_ga, rt_linux_5.15.71, smarc-8m-android-11.0.0_2.0.0, smarc-imx6_4.14.98_2.0.0_ga, smarc-imx6_4.9.88_2.0.0_ga, smarc-imx7_4.14.98_2.0.0_ga, smarc-imx7_4.9.11_1.0.0_ga, smarc-imx7_4.9.88_2.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-imx_4.1.15_1.0.0_ga, smarc-imx_4.9.11_1.0.0_ga, smarc-imx_4.9.51_imx8m_ga, smarc-imx_4.9.88_2.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_1.2.0_ga, smarc_8m_00d0_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.14.78_1.0.0_ga, smarc_8m_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.19.35_1.1.0, smarc_8mm_imx_4.14.78_1.0.0_ga, smarc_8mm_imx_4.14.98_2.0.0_ga, smarc_8mm_imx_4.19.35_1.1.0, smarc_8mm_imx_5.4.24_2.1.0, smarc_8mp_lf-5.10.y, smarc_8mq_imx_5.4.24_2.1.0, smarc_8mq_lf-5.10.y, smarc_imx_lf-5.15.y

ksm: drain pagevecs to lru 

It was hard to explain the page counts which were causing new LTP tests
of KSM to fail: we need to drain the per-cpu pagevecs to LRU occasionally.

Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: CAI Qian <caiqian@redhat.com>
Cc:Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 12 additions and 0 deletions Side-by-side Diff

... ... @@ -1296,6 +1296,18 @@
1296 1296  
1297 1297 slot = ksm_scan.mm_slot;
1298 1298 if (slot == &ksm_mm_head) {
  1299 + /*
  1300 + * A number of pages can hang around indefinitely on per-cpu
  1301 + * pagevecs, raised page count preventing write_protect_page
  1302 + * from merging them. Though it doesn't really matter much,
  1303 + * it is puzzling to see some stuck in pages_volatile until
  1304 + * other activity jostles them out, and they also prevented
  1305 + * LTP's KSM test from succeeding deterministically; so drain
  1306 + * them here (here rather than on entry to ksm_do_scan(),
  1307 + * so we don't IPI too often when pages_to_scan is set low).
  1308 + */
  1309 + lru_add_drain_all();
  1310 +
1299 1311 root_unstable_tree = RB_ROOT;
1300 1312  
1301 1313 spin_lock(&ksm_mmlist_lock);