[PATCH AUTOSEL 4.19 055/101] mm/swap: fix release_pages() when releasing devmap pages

[PATCH AUTOSEL 4.19 055/101] mm/swap: fix release_pages() when releasing devmap pages

[Sasha Levin]

From: Ira Weiny <ira.weiny@intel.com>

[ Upstream commit c5d6c45e90c49150670346967971e14576afd7f1 ]

release_pages() is an optimized version of a loop around put_page().
Unfortunately for devmap pages the logic is not entirely correct in
release_pages().  This is because device pages can be more than type
MEMORY_DEVICE_PUBLIC.  There are in fact 4 types, private, public, FS DAX,
and PCI P2PDMA.  Some of these have specific needs to "put" the page while
others do not.

This logic to handle any special needs is contained in
put_devmap_managed_page().  Therefore all devmap pages should be processed
by this function where we can contain the correct logic for a page put.

Handle all device type pages within release_pages() by calling
put_devmap_managed_page() on all devmap pages.  If
put_devmap_managed_page() returns true the page has been put and we
continue with the next page.  A false return of put_devmap_managed_page()
means the page did not require special processing and should fall to
"normal" processing.

This was found via code inspection while determining if release_pages()
and the new put_user_pages() could be interchangeable.[1]

[1] https://lkml.kernel.org/r/20190523172852.GA27175@iweiny-DESK2.sc.intel.com

Link: https://lkml.kernel.org/r/20190605214922.17684-1-ira.weiny@intel.com
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/swap.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index a3fc028e338e..45fdbfb6b2a6 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -740,15 +740,20 @@ void release_pages(struct page **pages, int nr)
 		if (is_huge_zero_page(page))
 			continue;
 
-		/* Device public page can not be huge page */
-		if (is_device_public_page(page)) {
+		if (is_zone_device_page(page)) {
 			if (locked_pgdat) {
 				spin_unlock_irqrestore(&locked_pgdat->lru_lock,
 						       flags);
 				locked_pgdat = NULL;
 			}
-			put_devmap_managed_page(page);
-			continue;
+			/*
+			 * ZONE_DEVICE pages that return 'false' from
+			 * put_devmap_managed_page() do not require special
+			 * processing, and instead, expect a call to
+			 * put_page_testzero().
+			 */
+			if (put_devmap_managed_page(page))
+				continue;
 		}
 
 		page = compound_head(page);
-- 
2.20.1

[PATCH AUTOSEL 4.19 088/101] mm/kmemleak.c: fix check for softirq context

[Sasha Levin]

From: Dmitry Vyukov <dvyukov@google.com>

[ Upstream commit 6ef9056952532c3b746de46aa10d45b4d7797bd8 ]

in_softirq() is a wrong predicate to check if we are in a softirq
context.  It also returns true if we have BH disabled, so objects are
falsely stamped with "softirq" comm.  The correct predicate is
in_serving_softirq().

If user does cat from /sys/kernel/debug/kmemleak previously they would
see this, which is clearly wrong, this is system call context (see the
comm):

unreferenced object 0xffff88805bd661c0 (size 64):
  comm "softirq", pid 0, jiffies 4294942959 (age 12.400s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 ff ff ff ff 00 00 00 00  ................
    00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
  backtrace:
    [<0000000007dcb30c>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline]
    [<0000000007dcb30c>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<0000000007dcb30c>] slab_alloc mm/slab.c:3326 [inline]
    [<0000000007dcb30c>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
    [<00000000969722b7>] kmalloc include/linux/slab.h:547 [inline]
    [<00000000969722b7>] kzalloc include/linux/slab.h:742 [inline]
    [<00000000969722b7>] ip_mc_add1_src net/ipv4/igmp.c:1961 [inline]
    [<00000000969722b7>] ip_mc_add_src+0x36b/0x400 net/ipv4/igmp.c:2085
    [<00000000a4134b5f>] ip_mc_msfilter+0x22d/0x310 net/ipv4/igmp.c:2475
    [<00000000d20248ad>] do_ip_setsockopt.isra.0+0x19fe/0x1c00 net/ipv4/ip_sockglue.c:957
    [<000000003d367be7>] ip_setsockopt+0x3b/0xb0 net/ipv4/ip_sockglue.c:1246
    [<000000003c7c76af>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
    [<000000000c1aeb23>] sock_common_setsockopt+0x3e/0x50 net/core/sock.c:3130
    [<000000000157b92b>] __sys_setsockopt+0x9e/0x120 net/socket.c:2078
    [<00000000a9f3d058>] __do_sys_setsockopt net/socket.c:2089 [inline]
    [<00000000a9f3d058>] __se_sys_setsockopt net/socket.c:2086 [inline]
    [<00000000a9f3d058>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
    [<000000001b8da885>] do_syscall_64+0x7c/0x1a0 arch/x86/entry/common.c:301
    [<00000000ba770c62>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

now they will see this:

unreferenced object 0xffff88805413c800 (size 64):
  comm "syz-executor.4", pid 8960, jiffies 4294994003 (age 14.350s)
  hex dump (first 32 bytes):
    00 7a 8a 57 80 88 ff ff e0 00 00 01 00 00 00 00  .z.W............
    00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000c5d3be64>] kmemleak_alloc_recursive include/linux/kmemleak.h:55 [inline]
    [<00000000c5d3be64>] slab_post_alloc_hook mm/slab.h:439 [inline]
    [<00000000c5d3be64>] slab_alloc mm/slab.c:3326 [inline]
    [<00000000c5d3be64>] kmem_cache_alloc_trace+0x13d/0x280 mm/slab.c:3553
    [<0000000023865be2>] kmalloc include/linux/slab.h:547 [inline]
    [<0000000023865be2>] kzalloc include/linux/slab.h:742 [inline]
    [<0000000023865be2>] ip_mc_add1_src net/ipv4/igmp.c:1961 [inline]
    [<0000000023865be2>] ip_mc_add_src+0x36b/0x400 net/ipv4/igmp.c:2085
    [<000000003029a9d4>] ip_mc_msfilter+0x22d/0x310 net/ipv4/igmp.c:2475
    [<00000000ccd0a87c>] do_ip_setsockopt.isra.0+0x19fe/0x1c00 net/ipv4/ip_sockglue.c:957
    [<00000000a85a3785>] ip_setsockopt+0x3b/0xb0 net/ipv4/ip_sockglue.c:1246
    [<00000000ec13c18d>] udp_setsockopt+0x4e/0x90 net/ipv4/udp.c:2616
    [<0000000052d748e3>] sock_common_setsockopt+0x3e/0x50 net/core/sock.c:3130
    [<00000000512f1014>] __sys_setsockopt+0x9e/0x120 net/socket.c:2078
    [<00000000181758bc>] __do_sys_setsockopt net/socket.c:2089 [inline]
    [<00000000181758bc>] __se_sys_setsockopt net/socket.c:2086 [inline]
    [<00000000181758bc>] __x64_sys_setsockopt+0x26/0x30 net/socket.c:2086
    [<00000000d4b73623>] do_syscall_64+0x7c/0x1a0 arch/x86/entry/common.c:301
    [<00000000c1098bec>] entry_SYSCALL_64_after_hwframe+0x44/0xa9

Link: http://lkml.kernel.org/r/20190517171507.96046-1-dvyukov@gmail.com
Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/kmemleak.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 72e3fb3bb037..6c94b6865ac2 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -576,7 +576,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
 	if (in_irq()) {
 		object->pid = 0;
 		strncpy(object->comm, "hardirq", sizeof(object->comm));
-	} else if (in_softirq()) {
+	} else if (in_serving_softirq()) {
 		object->pid = 0;
 		strncpy(object->comm, "softirq", sizeof(object->comm));
 	} else {
-- 
2.20.1

[PATCH AUTOSEL 4.19 090/101] mm/gup.c: mark undo_dev_pagemap as __maybe_unused

[Sasha Levin]

From: Guenter Roeck <linux@roeck-us.net>

[ Upstream commit 790c73690c2bbecb3f6f8becbdb11ddc9bcff8cc ]

Several mips builds generate the following build warning.

  mm/gup.c:1788:13: warning: 'undo_dev_pagemap' defined but not used

The function is declared unconditionally but only called from behind
various ifdefs. Mark it __maybe_unused.

Link: http://lkml.kernel.org/r/1562072523-22311-1-git-send-email-linux@roeck-us.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/gup.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/gup.c b/mm/gup.c
index caadd31714a5..43c71397c7ca 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1367,7 +1367,8 @@ static inline pte_t gup_get_pte(pte_t *ptep)
 }
 #endif
 
-static void undo_dev_pagemap(int *nr, int nr_start, struct page **pages)
+static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start,
+					    struct page **pages)
 {
 	while ((*nr) - nr_start) {
 		struct page *page = pages[--(*nr)];
-- 
2.20.1

[PATCH AUTOSEL 4.19 091/101] mm/gup.c: remove some BUG_ONs from get_gate_page()

[Sasha Levin]

From: Andy Lutomirski <luto@kernel.org>

[ Upstream commit b5d1c39f34d1c9bca0c4b9ae2e339fbbe264a9c7 ]

If we end up without a PGD or PUD entry backing the gate area, don't BUG
-- just fail gracefully.

It's not entirely implausible that this could happen some day on x86.  It
doesn't right now even with an execute-only emulated vsyscall page because
the fixmap shares the PUD, but the core mm code shouldn't rely on that
particular detail to avoid OOPSing.

Link: http://lkml.kernel.org/r/a1d9f4efb75b9d464e59fd6af00104b21c58f6f7.1561610798.git.luto@kernel.org
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/gup.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 43c71397c7ca..f3088d25bd92 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -458,11 +458,14 @@ static int get_gate_page(struct mm_struct *mm, unsigned long address,
 		pgd = pgd_offset_k(address);
 	else
 		pgd = pgd_offset_gate(mm, address);
-	BUG_ON(pgd_none(*pgd));
+	if (pgd_none(*pgd))
+		return -EFAULT;
 	p4d = p4d_offset(pgd, address);
-	BUG_ON(p4d_none(*p4d));
+	if (p4d_none(*p4d))
+		return -EFAULT;
 	pud = pud_offset(p4d, address);
-	BUG_ON(pud_none(*pud));
+	if (pud_none(*pud))
+		return -EFAULT;
 	pmd = pmd_offset(pud, address);
 	if (!pmd_present(*pmd))
 		return -EFAULT;
-- 
2.20.1

[PATCH AUTOSEL 4.19 093/101] mm/mmu_notifier: use hlist_add_head_rcu()

[Sasha Levin]

From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>

[ Upstream commit 543bdb2d825fe2400d6e951f1786d92139a16931 ]

Make mmu_notifier_register() safer by issuing a memory barrier before
registering a new notifier.  This fixes a theoretical bug on weakly
ordered CPUs.  For example, take this simplified use of notifiers by a
driver:

	my_struct->mn.ops = &my_ops; /* (1) */
	mmu_notifier_register(&my_struct->mn, mm)
		...
		hlist_add_head(&mn->hlist, &mm->mmu_notifiers); /* (2) */
		...

Once mmu_notifier_register() releases the mm locks, another thread can
invalidate a range:

	mmu_notifier_invalidate_range()
		...
		hlist_for_each_entry_rcu(mn, &mm->mmu_notifiers, hlist) {
			if (mn->ops->invalidate_range)

The read side relies on the data dependency between mn and ops to ensure
that the pointer is properly initialized.  But the write side doesn't have
any dependency between (1) and (2), so they could be reordered and the
readers could dereference an invalid mn->ops.  mmu_notifier_register()
does take all the mm locks before adding to the hlist, but those have
acquire semantics which isn't sufficient.

By calling hlist_add_head_rcu() instead of hlist_add_head() we update the
hlist using a store-release, ensuring that readers see prior
initialization of my_struct.  This situation is better illustated by
litmus test MP+onceassign+derefonce.

Link: http://lkml.kernel.org/r/20190502133532.24981-1-jean-philippe.brucker@arm.com
Fixes: cddb8a5c14aa ("mmu-notifiers: core")
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/mmu_notifier.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c
index 82bb1a939c0e..06dedb175572 100644
--- a/mm/mmu_notifier.c
+++ b/mm/mmu_notifier.c
@@ -316,7 +316,7 @@ static int do_mmu_notifier_register(struct mmu_notifier *mn,
 	 * thanks to mm_take_all_locks().
 	 */
 	spin_lock(&mm->mmu_notifier_mm->lock);
-	hlist_add_head(&mn->hlist, &mm->mmu_notifier_mm->list);
+	hlist_add_head_rcu(&mn->hlist, &mm->mmu_notifier_mm->list);
 	spin_unlock(&mm->mmu_notifier_mm->lock);
 
 	mm_drop_all_locks(mm);
-- 
2.20.1

[PATCH AUTOSEL 4.19 101/101] mm: use down_read_killable for locking mmap_sem in access_remote_vm

[Sasha Levin]

From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

[ Upstream commit 1e426fe28261b03f297992e89da3320b42816f4e ]

This function is used by ptrace and proc files like /proc/pid/cmdline and
/proc/pid/environ.

Access_remote_vm never returns error codes, all errors are ignored and
only size of successfully read data is returned.  So, if current task was
killed we'll simply return 0 (bytes read).

Mmap_sem could be locked for a long time or forever if something goes
wrong.  Using a killable lock permits cleanup of stuck tasks and
simplifies investigation.

Link: http://lkml.kernel.org/r/156007494202.3335.16782303099589302087.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 mm/memory.c | 4 +++-
 mm/nommu.c  | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index e0010cb870e0..fb5655b518c9 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4491,7 +4491,9 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 	void *old_buf = buf;
 	int write = gup_flags & FOLL_WRITE;
 
-	down_read(&mm->mmap_sem);
+	if (down_read_killable(&mm->mmap_sem))
+		return 0;
+
 	/* ignore errors, just check how much was successfully transferred */
 	while (len) {
 		int bytes, ret, offset;
diff --git a/mm/nommu.c b/mm/nommu.c
index e4aac33216ae..1d63ecfc98c5 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1779,7 +1779,8 @@ int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
 	struct vm_area_struct *vma;
 	int write = gup_flags & FOLL_WRITE;
 
-	down_read(&mm->mmap_sem);
+	if (down_read_killable(&mm->mmap_sem))
+		return 0;
 
 	/* the access must start within one of the target process's mappings */
 	vma = find_vma(mm, addr);
-- 
2.20.1