| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <tip-a54a407fbf7735fd8f7841375574f5d9b0375f93@git.kernel.org>
Date: Wed, 9 Oct 2013 10:25:12 -0700
From: tip-bot for Mel Gorman <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
peterz@...radead.org, hannes@...xchg.org, riel@...hat.com,
aarcange@...hat.com, srikar@...ux.vnet.ibm.com, mgorman@...e.de,
tglx@...utronix.de
Subject: [tip:sched/core] mm:
Close races between THP migration and PMD numa clearing
Commit-ID: a54a407fbf7735fd8f7841375574f5d9b0375f93
Gitweb: http://git.kernel.org/tip/a54a407fbf7735fd8f7841375574f5d9b0375f93
Author: Mel Gorman <mgorman@...e.de>
AuthorDate: Mon, 7 Oct 2013 11:28:46 +0100
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 9 Oct 2013 12:39:45 +0200
mm: Close races between THP migration and PMD numa clearing
THP migration uses the page lock to guard against parallel allocations
but there are cases like this still open
Task A Task B
--------------------- ---------------------
do_huge_pmd_numa_page do_huge_pmd_numa_page
lock_page
mpol_misplaced == -1
unlock_page
goto clear_pmdnuma
lock_page
mpol_misplaced == 2
migrate_misplaced_transhuge
pmd = pmd_mknonnuma
set_pmd_at
During hours of testing, one crashed with weird errors and while I have
no direct evidence, I suspect something like the race above happened.
This patch extends the page lock to being held until the pmd_numa is
cleared to prevent migration starting in parallel while the pmd_numa is
being cleared. It also flushes the old pmd entry and orders pagetable
insertion before rmap insertion.
Signed-off-by: Mel Gorman <mgorman@...e.de>
Reviewed-by: Rik van Riel <riel@...hat.com>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@...radead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-9-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
mm/huge_memory.c | 33 +++++++++++++++------------------
mm/migrate.c | 19 +++++++++++--------
2 files changed, 26 insertions(+), 26 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index c3bb65f..d4928769 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1304,24 +1304,25 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
target_nid = mpol_misplaced(page, vma, haddr);
if (target_nid == -1) {
/* If the page was locked, there are no parallel migrations */
- if (page_locked) {
- unlock_page(page);
+ if (page_locked)
goto clear_pmdnuma;
- }
- /* Otherwise wait for potential migrations and retry fault */
+ /*
+ * Otherwise wait for potential migrations and retry. We do
+ * relock and check_same as the page may no longer be mapped.
+ * As the fault is being retried, do not account for it.
+ */
spin_unlock(&mm->page_table_lock);
wait_on_page_locked(page);
+ page_nid = -1;
goto out;
}
/* Page is misplaced, serialise migrations and parallel THP splits */
get_page(page);
spin_unlock(&mm->page_table_lock);
- if (!page_locked) {
+ if (!page_locked)
lock_page(page);
- page_locked = true;
- }
anon_vma = page_lock_anon_vma_read(page);
/* Confirm the PMD did not change while page_table_lock was released */
@@ -1329,32 +1330,28 @@ int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
if (unlikely(!pmd_same(pmd, *pmdp))) {
unlock_page(page);
put_page(page);
+ page_nid = -1;
goto out_unlock;
}
- /* Migrate the THP to the requested node */
+ /*
+ * Migrate the THP to the requested node, returns with page unlocked
+ * and pmd_numa cleared.
+ */
spin_unlock(&mm->page_table_lock);
migrated = migrate_misplaced_transhuge_page(mm, vma,
pmdp, pmd, addr, page, target_nid);
if (migrated)
page_nid = target_nid;
- else
- goto check_same;
goto out;
-
-check_same:
- spin_lock(&mm->page_table_lock);
- if (unlikely(!pmd_same(pmd, *pmdp))) {
- /* Someone else took our fault */
- page_nid = -1;
- goto out_unlock;
- }
clear_pmdnuma:
+ BUG_ON(!PageLocked(page));
pmd = pmd_mknonnuma(pmd);
set_pmd_at(mm, haddr, pmdp, pmd);
VM_BUG_ON(pmd_numa(*pmdp));
update_mmu_cache_pmd(vma, addr, pmdp);
+ unlock_page(page);
out_unlock:
spin_unlock(&mm->page_table_lock);
diff --git a/mm/migrate.c b/mm/migrate.c
index a26bccd..7bd90d3 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1713,12 +1713,12 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
unlock_page(new_page);
put_page(new_page); /* Free it */
- unlock_page(page);
+ /* Retake the callers reference and putback on LRU */
+ get_page(page);
putback_lru_page(page);
-
- count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
- isolated = 0;
- goto out;
+ mod_zone_page_state(page_zone(page),
+ NR_ISOLATED_ANON + page_lru, -HPAGE_PMD_NR);
+ goto out_fail;
}
/*
@@ -1735,9 +1735,9 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
entry = pmd_mkhuge(entry);
- page_add_new_anon_rmap(new_page, vma, haddr);
-
+ pmdp_clear_flush(vma, haddr, pmd);
set_pmd_at(mm, haddr, pmd, entry);
+ page_add_new_anon_rmap(new_page, vma, haddr);
update_mmu_cache_pmd(vma, address, &entry);
page_remove_rmap(page);
/*
@@ -1756,7 +1756,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm,
count_vm_events(PGMIGRATE_SUCCESS, HPAGE_PMD_NR);
count_vm_numa_events(NUMA_PAGE_MIGRATE, HPAGE_PMD_NR);
-out:
mod_zone_page_state(page_zone(page),
NR_ISOLATED_ANON + page_lru,
-HPAGE_PMD_NR);
@@ -1765,6 +1764,10 @@ out:
out_fail:
count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR);
out_dropref:
+ entry = pmd_mknonnuma(entry);
+ set_pmd_at(mm, haddr, pmd, entry);
+ update_mmu_cache_pmd(vma, address, &entry);
+
unlock_page(page);
put_page(page);
return 0;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists