The quilt patch titled
Subject: Revert "selftests/mm: fix deadlock for fork after pthread_create on ARM"
has been removed from the -mm tree. Its filename was
revert-selftests-mm-fix-deadlock-for-fork-after-pthread_create-on-arm.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Edward Liaw <edliaw(a)google.com>
Subject: Revert "selftests/mm: fix deadlock for fork after pthread_create on ARM"
Date: Fri, 18 Oct 2024 17:17:22 +0000
Patch series "selftests/mm: revert pthread_barrier change"
On Android arm, pthread_create followed by a fork caused a deadlock in
the case where the fork required work to be completed by the created
thread.
The previous patches incorrectly assumed that the parent would
always initialize the pthread_barrier for the child thread. This
reverts the change and replaces the fix for wp-fork-with-event with the
original use of atomic_bool.
This patch (of 3):
This reverts commit e142cc87ac4ec618f2ccf5f68aedcd6e28a59d9d.
fork_event_consumer may be called by other tests that do not initialize
the pthread_barrier, so this approach is not correct. The subsequent
patch will revert to using atomic_bool instead.
Link: https://lkml.kernel.org/r/20241018171734.2315053-1-edliaw@google.com
Link: https://lkml.kernel.org/r/20241018171734.2315053-2-edliaw@google.com
Fixes: e142cc87ac4e ("fix deadlock for fork after pthread_create on ARM")
Signed-off-by: Edward Liaw <edliaw(a)google.com>
Cc: Ryan Roberts <ryan.roberts(a)arm.com>
Cc: Peter Xu <peterx(a)redhat.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
tools/testing/selftests/mm/uffd-unit-tests.c | 7 -------
1 file changed, 7 deletions(-)
--- a/tools/testing/selftests/mm/uffd-unit-tests.c~revert-selftests-mm-fix-deadlock-for-fork-after-pthread_create-on-arm
+++ a/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -241,9 +241,6 @@ static void *fork_event_consumer(void *d
fork_event_args *args = data;
struct uffd_msg msg = { 0 };
- /* Ready for parent thread to fork */
- pthread_barrier_wait(&ready_for_fork);
-
/* Read until a full msg received */
while (uffd_read_msg(args->parent_uffd, &msg));
@@ -311,12 +308,8 @@ static int pagemap_test_fork(int uffd, b
/* Prepare a thread to resolve EVENT_FORK */
if (with_event) {
- pthread_barrier_init(&ready_for_fork, NULL, 2);
if (pthread_create(&thread, NULL, fork_event_consumer, &args))
err("pthread_create()");
- /* Wait for child thread to start before forking */
- pthread_barrier_wait(&ready_for_fork);
- pthread_barrier_destroy(&ready_for_fork);
}
child = fork();
_
Patches currently in -mm which might be from edliaw(a)google.com are
The quilt patch titled
Subject: nilfs2: fix kernel bug due to missing clearing of checked flag
has been removed from the -mm tree. Its filename was
nilfs2-fix-kernel-bug-due-to-missing-clearing-of-checked-flag.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Ryusuke Konishi <konishi.ryusuke(a)gmail.com>
Subject: nilfs2: fix kernel bug due to missing clearing of checked flag
Date: Fri, 18 Oct 2024 04:33:10 +0900
Syzbot reported that in directory operations after nilfs2 detects
filesystem corruption and degrades to read-only,
__block_write_begin_int(), which is called to prepare block writes, may
fail the BUG_ON check for accesses exceeding the folio/page size,
triggering a kernel bug.
This was found to be because the "checked" flag of a page/folio was not
cleared when it was discarded by nilfs2's own routine, which causes the
sanity check of directory entries to be skipped when the directory
page/folio is reloaded. So, fix that.
This was necessary when the use of nilfs2's own page discard routine was
applied to more than just metadata files.
Link: https://lkml.kernel.org/r/20241017193359.5051-1-konishi.ryusuke@gmail.com
Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke(a)gmail.com>
Reported-by: syzbot+d6ca2daf692c7a82f959(a)syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d6ca2daf692c7a82f959
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
fs/nilfs2/page.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/nilfs2/page.c~nilfs2-fix-kernel-bug-due-to-missing-clearing-of-checked-flag
+++ a/fs/nilfs2/page.c
@@ -400,6 +400,7 @@ void nilfs_clear_folio_dirty(struct foli
folio_clear_uptodate(folio);
folio_clear_mappedtodisk(folio);
+ folio_clear_checked(folio);
head = folio_buffers(folio);
if (head) {
_
Patches currently in -mm which might be from konishi.ryusuke(a)gmail.com are
nilfs2-fix-potential-deadlock-with-newly-created-symlinks.patch
The quilt patch titled
Subject: ocfs2: pass u64 to ocfs2_truncate_inline maybe overflow
has been removed from the -mm tree. Its filename was
ocfs2-pass-u64-to-ocfs2_truncate_inline-maybe-overflow.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Edward Adam Davis <eadavis(a)qq.com>
Subject: ocfs2: pass u64 to ocfs2_truncate_inline maybe overflow
Date: Wed, 16 Oct 2024 19:43:47 +0800
Syzbot reported a kernel BUG in ocfs2_truncate_inline. There are two
reasons for this: first, the parameter value passed is greater than
ocfs2_max_inline_data_with_xattr, second, the start and end parameters of
ocfs2_truncate_inline are "unsigned int".
So, we need to add a sanity check for byte_start and byte_len right before
ocfs2_truncate_inline() in ocfs2_remove_inode_range(), if they are greater
than ocfs2_max_inline_data_with_xattr return -EINVAL.
Link: https://lkml.kernel.org/r/tencent_D48DB5122ADDAEDDD11918CFB68D93258C07@qq.c…
Fixes: 1afc32b95233 ("ocfs2: Write support for inline data")
Signed-off-by: Edward Adam Davis <eadavis(a)qq.com>
Reported-by: syzbot+81092778aac03460d6b7(a)syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=81092778aac03460d6b7
Reviewed-by: Joseph Qi <joseph.qi(a)linux.alibaba.com>
Cc: Joel Becker <jlbec(a)evilplan.org>
Cc: Joseph Qi <joseph.qi(a)linux.alibaba.com>
Cc: Mark Fasheh <mark(a)fasheh.com>
Cc: Junxiao Bi <junxiao.bi(a)oracle.com>
Cc: Changwei Ge <gechangwei(a)live.cn>
Cc: Gang He <ghe(a)suse.com>
Cc: Jun Piao <piaojun(a)huawei.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
fs/ocfs2/file.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/fs/ocfs2/file.c~ocfs2-pass-u64-to-ocfs2_truncate_inline-maybe-overflow
+++ a/fs/ocfs2/file.c
@@ -1784,6 +1784,14 @@ int ocfs2_remove_inode_range(struct inod
return 0;
if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
+ int id_count = ocfs2_max_inline_data_with_xattr(inode->i_sb, di);
+
+ if (byte_start > id_count || byte_start + byte_len > id_count) {
+ ret = -EINVAL;
+ mlog_errno(ret);
+ goto out;
+ }
+
ret = ocfs2_truncate_inline(inode, di_bh, byte_start,
byte_start + byte_len, 0);
if (ret) {
_
Patches currently in -mm which might be from eadavis(a)qq.com are
The quilt patch titled
Subject: mm: shmem: fix data-race in shmem_getattr()
has been removed from the -mm tree. Its filename was
mm-shmem-fix-data-race-in-shmem_getattr.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Jeongjun Park <aha310510(a)gmail.com>
Subject: mm: shmem: fix data-race in shmem_getattr()
Date: Mon, 9 Sep 2024 21:35:58 +0900
I got the following KCSAN report during syzbot testing:
==================================================================
BUG: KCSAN: data-race in generic_fillattr / inode_set_ctime_current
write to 0xffff888102eb3260 of 4 bytes by task 6565 on cpu 1:
inode_set_ctime_to_ts include/linux/fs.h:1638 [inline]
inode_set_ctime_current+0x169/0x1d0 fs/inode.c:2626
shmem_mknod+0x117/0x180 mm/shmem.c:3443
shmem_create+0x34/0x40 mm/shmem.c:3497
lookup_open fs/namei.c:3578 [inline]
open_last_lookups fs/namei.c:3647 [inline]
path_openat+0xdbc/0x1f00 fs/namei.c:3883
do_filp_open+0xf7/0x200 fs/namei.c:3913
do_sys_openat2+0xab/0x120 fs/open.c:1416
do_sys_open fs/open.c:1431 [inline]
__do_sys_openat fs/open.c:1447 [inline]
__se_sys_openat fs/open.c:1442 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1442
x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x76/0x7e
read to 0xffff888102eb3260 of 4 bytes by task 3498 on cpu 0:
inode_get_ctime_nsec include/linux/fs.h:1623 [inline]
inode_get_ctime include/linux/fs.h:1629 [inline]
generic_fillattr+0x1dd/0x2f0 fs/stat.c:62
shmem_getattr+0x17b/0x200 mm/shmem.c:1157
vfs_getattr_nosec fs/stat.c:166 [inline]
vfs_getattr+0x19b/0x1e0 fs/stat.c:207
vfs_statx_path fs/stat.c:251 [inline]
vfs_statx+0x134/0x2f0 fs/stat.c:315
vfs_fstatat+0xec/0x110 fs/stat.c:341
__do_sys_newfstatat fs/stat.c:505 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:499
__x64_sys_newfstatat+0x55/0x70 fs/stat.c:499
x64_sys_call+0x141f/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:263
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x76/0x7e
value changed: 0x2755ae53 -> 0x27ee44d3
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3498 Comm: udevd Not tainted 6.11.0-rc6-syzkaller-00326-gd1f2d51b711a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
==================================================================
When calling generic_fillattr(), if you don't hold read lock, data-race
will occur in inode member variables, which can cause unexpected
behavior.
Since there is no special protection when shmem_getattr() calls
generic_fillattr(), data-race occurs by functions such as shmem_unlink()
or shmem_mknod(). This can cause unexpected results, so commenting it out
is not enough.
Therefore, when calling generic_fillattr() from shmem_getattr(), it is
appropriate to protect the inode using inode_lock_shared() and
inode_unlock_shared() to prevent data-race.
Link: https://lkml.kernel.org/r/20240909123558.70229-1-aha310510@gmail.com
Fixes: 44a30220bc0a ("shmem: recalculate file inode when fstat")
Signed-off-by: Jeongjun Park <aha310510(a)gmail.com>
Reported-by: syzbot <syzkaller(a)googlegroup.com>
Cc: Hugh Dickins <hughd(a)google.com>
Cc: Yu Zhao <yuzhao(a)google.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/shmem.c | 2 ++
1 file changed, 2 insertions(+)
--- a/mm/shmem.c~mm-shmem-fix-data-race-in-shmem_getattr
+++ a/mm/shmem.c
@@ -1166,7 +1166,9 @@ static int shmem_getattr(struct mnt_idma
stat->attributes_mask |= (STATX_ATTR_APPEND |
STATX_ATTR_IMMUTABLE |
STATX_ATTR_NODUMP);
+ inode_lock_shared(inode);
generic_fillattr(idmap, request_mask, inode, stat);
+ inode_unlock_shared(inode);
if (shmem_huge_global_enabled(inode, 0, 0, false, NULL, 0))
stat->blksize = HPAGE_PMD_SIZE;
_
Patches currently in -mm which might be from aha310510(a)gmail.com are
The quilt patch titled
Subject: x86/traps: move kmsan check after instrumentation_begin
has been removed from the -mm tree. Its filename was
x86-traps-move-kmsan-check-after-instrumentation_begin.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Sabyrzhan Tasbolatov <snovitoll(a)gmail.com>
Subject: x86/traps: move kmsan check after instrumentation_begin
Date: Wed, 16 Oct 2024 20:24:07 +0500
During x86_64 kernel build with CONFIG_KMSAN, the objtool warns following:
AR built-in.a
AR vmlinux.a
LD vmlinux.o
vmlinux.o: warning: objtool: handle_bug+0x4: call to
kmsan_unpoison_entry_regs() leaves .noinstr.text section
OBJCOPY modules.builtin.modinfo
GEN modules.builtin
MODPOST Module.symvers
CC .vmlinux.export.o
Moving kmsan_unpoison_entry_regs() _after_ instrumentation_begin() fixes
the warning.
There is decode_bug(regs->ip, &imm) is left before KMSAN unpoisoining, but
it has the return condition and if we include it after
instrumentation_begin() it results the warning "return with
instrumentation enabled", hence, I'm concerned that regs will not be KMSAN
unpoisoned if `ud_type == BUG_NONE` is true.
Link: https://lkml.kernel.org/r/20241016152407.3149001-1-snovitoll@gmail.com
Fixes: ba54d194f8da ("x86/traps: avoid KMSAN bugs originating from handle_bug()")
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll(a)gmail.com>
Reviewed-by: Alexander Potapenko <glider(a)google.com>
Cc: Borislav Petkov (AMD) <bp(a)alien8.de>
Cc: Dave Hansen <dave.hansen(a)linux.intel.com>
Cc: Ingo Molnar <mingo(a)redhat.com>
Cc: Thomas Gleixner <tglx(a)linutronix.de>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
arch/x86/kernel/traps.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
--- a/arch/x86/kernel/traps.c~x86-traps-move-kmsan-check-after-instrumentation_begin
+++ a/arch/x86/kernel/traps.c
@@ -261,12 +261,6 @@ static noinstr bool handle_bug(struct pt
int ud_type;
u32 imm;
- /*
- * Normally @regs are unpoisoned by irqentry_enter(), but handle_bug()
- * is a rare case that uses @regs without passing them to
- * irqentry_enter().
- */
- kmsan_unpoison_entry_regs(regs);
ud_type = decode_bug(regs->ip, &imm);
if (ud_type == BUG_NONE)
return handled;
@@ -276,6 +270,12 @@ static noinstr bool handle_bug(struct pt
*/
instrumentation_begin();
/*
+ * Normally @regs are unpoisoned by irqentry_enter(), but handle_bug()
+ * is a rare case that uses @regs without passing them to
+ * irqentry_enter().
+ */
+ kmsan_unpoison_entry_regs(regs);
+ /*
* Since we're emulating a CALL with exceptions, restore the interrupt
* state to what it was at the exception site.
*/
_
Patches currently in -mm which might be from snovitoll(a)gmail.com are
mm-kasan-kmsan-copy_from-to_kernel_nofault.patch
kasan-move-checks-to-do_strncpy_from_user.patch
kasan-migrate-copy_user_test-to-kunit.patch
kasan-delete-config_kasan_module_test.patch
kasan-delete-config_kasan_module_test-fix.patch
The quilt patch titled
Subject: mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves
has been removed from the -mm tree. Its filename was
mm-page_alloc-let-gfp_atomic-order-0-allocs-access-highatomic-reserves.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Matt Fleming <mfleming(a)cloudflare.com>
Subject: mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves
Date: Fri, 11 Oct 2024 13:07:37 +0100
Under memory pressure it's possible for GFP_ATOMIC order-0 allocations to
fail even though free pages are available in the highatomic reserves.
GFP_ATOMIC allocations cannot trigger unreserve_highatomic_pageblock()
since it's only run from reclaim.
Given that such allocations will pass the watermarks in
__zone_watermark_unusable_free(), it makes sense to fallback to highatomic
reserves the same way that ALLOC_OOM can.
This fixes order-0 page allocation failures observed on Cloudflare's fleet
when handling network packets:
kswapd1: page allocation failure: order:0, mode:0x820(GFP_ATOMIC),
nodemask=(null),cpuset=/,mems_allowed=0-7
CPU: 10 PID: 696 Comm: kswapd1 Kdump: loaded Tainted: G O 6.6.43-CUSTOM #1
Hardware name: MACHINE
Call Trace:
<IRQ>
dump_stack_lvl+0x3c/0x50
warn_alloc+0x13a/0x1c0
__alloc_pages_slowpath.constprop.0+0xc9d/0xd10
__alloc_pages+0x327/0x340
__napi_alloc_skb+0x16d/0x1f0
bnxt_rx_page_skb+0x96/0x1b0 [bnxt_en]
bnxt_rx_pkt+0x201/0x15e0 [bnxt_en]
__bnxt_poll_work+0x156/0x2b0 [bnxt_en]
bnxt_poll+0xd9/0x1c0 [bnxt_en]
__napi_poll+0x2b/0x1b0
bpf_trampoline_6442524138+0x7d/0x1000
__napi_poll+0x5/0x1b0
net_rx_action+0x342/0x740
handle_softirqs+0xcf/0x2b0
irq_exit_rcu+0x6c/0x90
sysvec_apic_timer_interrupt+0x72/0x90
</IRQ>
[mfleming(a)cloudflare.com: update comment]
Link: https://lkml.kernel.org/r/20241015125158.3597702-1-matt@readmodwrite.com
Link: https://lkml.kernel.org/r/20241011120737.3300370-1-matt@readmodwrite.com
Link: https://lore.kernel.org/all/CAGis_TWzSu=P7QJmjD58WWiu3zjMTVKSzdOwWE8ORaGytz…
Fixes: 1d91df85f399 ("mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs")
Signed-off-by: Matt Fleming <mfleming(a)cloudflare.com>
Suggested-by: Vlastimil Babka <vbabka(a)suse.cz>
Reviewed-by: Vlastimil Babka <vbabka(a)suse.cz>
Cc: Mel Gorman <mgorman(a)techsingularity.net>
Cc: Michal Hocko <mhocko(a)kernel.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/page_alloc.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
--- a/mm/page_alloc.c~mm-page_alloc-let-gfp_atomic-order-0-allocs-access-highatomic-reserves
+++ a/mm/page_alloc.c
@@ -2893,12 +2893,12 @@ struct page *rmqueue_buddy(struct zone *
page = __rmqueue(zone, order, migratetype, alloc_flags);
/*
- * If the allocation fails, allow OOM handling access
- * to HIGHATOMIC reserves as failing now is worse than
- * failing a high-order atomic allocation in the
- * future.
+ * If the allocation fails, allow OOM handling and
+ * order-0 (atomic) allocs access to HIGHATOMIC
+ * reserves as failing now is worse than failing a
+ * high-order atomic allocation in the future.
*/
- if (!page && (alloc_flags & ALLOC_OOM))
+ if (!page && (alloc_flags & (ALLOC_OOM|ALLOC_NON_BLOCK)))
page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC);
if (!page) {
_
Patches currently in -mm which might be from mfleming(a)cloudflare.com are
The quilt patch titled
Subject: fork: only invoke khugepaged, ksm hooks if no error
has been removed from the -mm tree. Its filename was
fork-only-invoke-khugepaged-ksm-hooks-if-no-error.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Subject: fork: only invoke khugepaged, ksm hooks if no error
Date: Tue, 15 Oct 2024 18:56:06 +0100
There is no reason to invoke these hooks early against an mm that is in an
incomplete state.
The change in commit d24062914837 ("fork: use __mt_dup() to duplicate
maple tree in dup_mmap()") makes this more pertinent as we may be in a
state where entries in the maple tree are not yet consistent.
Their placement early in dup_mmap() only appears to have been meaningful
for early error checking, and since functionally it'd require a very small
allocation to fail (in practice 'too small to fail') that'd only occur in
the most dire circumstances, meaning the fork would fail or be OOM'd in
any case.
Since both khugepaged and KSM tracking are there to provide optimisations
to memory performance rather than critical functionality, it doesn't
really matter all that much if, under such dire memory pressure, we fail
to register an mm with these.
As a result, we follow the example of commit d2081b2bf819 ("mm:
khugepaged: make khugepaged_enter() void function") and make ksm_fork() a
void function also.
We only expose the mm to these functions once we are done with them and
only if no error occurred in the fork operation.
Link: https://lkml.kernel.org/r/e0cb8b840c9d1d5a6e84d4f8eff5f3f2022aa10c.17290143…
Fixes: d24062914837 ("fork: use __mt_dup() to duplicate maple tree in dup_mmap()")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Reported-by: Jann Horn <jannh(a)google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett(a)Oracle.com>
Reviewed-by: Vlastimil Babka <vbabka(a)suse.cz>
Reviewed-by: Jann Horn <jannh(a)google.com>
Cc: Alexander Viro <viro(a)zeniv.linux.org.uk>
Cc: Christian Brauner <brauner(a)kernel.org>
Cc: Jan Kara <jack(a)suse.cz>
Cc: Linus Torvalds <torvalds(a)linuxfoundation.org>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
include/linux/ksm.h | 10 ++++------
kernel/fork.c | 7 ++-----
2 files changed, 6 insertions(+), 11 deletions(-)
--- a/include/linux/ksm.h~fork-only-invoke-khugepaged-ksm-hooks-if-no-error
+++ a/include/linux/ksm.h
@@ -54,12 +54,11 @@ static inline long mm_ksm_zero_pages(str
return atomic_long_read(&mm->ksm_zero_pages);
}
-static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
+static inline void ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
+ /* Adding mm to ksm is best effort on fork. */
if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
- return __ksm_enter(mm);
-
- return 0;
+ __ksm_enter(mm);
}
static inline int ksm_execve(struct mm_struct *mm)
@@ -107,9 +106,8 @@ static inline int ksm_disable(struct mm_
return 0;
}
-static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
+static inline void ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
{
- return 0;
}
static inline int ksm_execve(struct mm_struct *mm)
--- a/kernel/fork.c~fork-only-invoke-khugepaged-ksm-hooks-if-no-error
+++ a/kernel/fork.c
@@ -653,11 +653,6 @@ static __latent_entropy int dup_mmap(str
mm->exec_vm = oldmm->exec_vm;
mm->stack_vm = oldmm->stack_vm;
- retval = ksm_fork(mm, oldmm);
- if (retval)
- goto out;
- khugepaged_fork(mm, oldmm);
-
/* Use __mt_dup() to efficiently build an identical maple tree. */
retval = __mt_dup(&oldmm->mm_mt, &mm->mm_mt, GFP_KERNEL);
if (unlikely(retval))
@@ -760,6 +755,8 @@ loop_out:
vma_iter_free(&vmi);
if (!retval) {
mt_set_in_rcu(vmi.mas.tree);
+ ksm_fork(mm, oldmm);
+ khugepaged_fork(mm, oldmm);
} else if (mpnt) {
/*
* The entire maple tree has already been duplicated. If the
_
Patches currently in -mm which might be from lorenzo.stoakes(a)oracle.com are
mm-avoid-unsafe-vma-hook-invocation-when-error-arises-on-mmap-hook.patch
mm-unconditionally-close-vmas-on-error.patch
mm-refactor-map_deny_write_exec.patch
mm-resolve-faulty-mmap_region-error-path-behaviour.patch
selftests-mm-add-pkey_sighandler_xx-hugetlb_dio-to-gitignore.patch
mm-refactor-mm_access-to-not-return-null.patch
mm-refactor-mm_access-to-not-return-null-fix.patch
mm-madvise-unrestrict-process_madvise-for-current-process.patch
maple_tree-do-not-hash-pointers-on-dump-in-debug-mode.patch
tools-testing-fix-phys_addr_t-size-on-64-bit-systems.patch
tools-testing-fix-phys_addr_t-size-on-64-bit-systems-fix.patch
tools-testing-add-additional-vma_internalh-stubs.patch
mm-isolate-mmap-internal-logic-to-mm-vmac.patch
mm-refactor-__mmap_region.patch
mm-defer-second-attempt-at-merge-on-mmap.patch
mm-pagewalk-add-the-ability-to-install-ptes.patch
mm-add-pte_marker_guard-pte-marker.patch
mm-madvise-implement-lightweight-guard-page-mechanism.patch
tools-testing-update-tools-uapi-header-for-mman-commonh.patch
selftests-mm-add-self-tests-for-guard-page-feature.patch
The quilt patch titled
Subject: fork: do not invoke uffd on fork if error occurs
has been removed from the -mm tree. Its filename was
fork-do-not-invoke-uffd-on-fork-if-error-occurs.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Subject: fork: do not invoke uffd on fork if error occurs
Date: Tue, 15 Oct 2024 18:56:05 +0100
Patch series "fork: do not expose incomplete mm on fork".
During fork we may place the virtual memory address space into an
inconsistent state before the fork operation is complete.
In addition, we may encounter an error during the fork operation that
indicates that the virtual memory address space is invalidated.
As a result, we should not be exposing it in any way to external machinery
that might interact with the mm or VMAs, machinery that is not designed to
deal with incomplete state.
We specifically update the fork logic to defer khugepaged and ksm to the
end of the operation and only to be invoked if no error arose, and
disallow uffd from observing fork events should an error have occurred.
This patch (of 2):
Currently on fork we expose the virtual address space of a process to
userland unconditionally if uffd is registered in VMAs, regardless of
whether an error arose in the fork.
This is performed in dup_userfaultfd_complete() which is invoked
unconditionally, and performs two duties - invoking registered handlers
for the UFFD_EVENT_FORK event via dup_fctx(), and clearing down
userfaultfd_fork_ctx objects established in dup_userfaultfd().
This is problematic, because the virtual address space may not yet be
correctly initialised if an error arose.
The change in commit d24062914837 ("fork: use __mt_dup() to duplicate
maple tree in dup_mmap()") makes this more pertinent as we may be in a
state where entries in the maple tree are not yet consistent.
We address this by, on fork error, ensuring that we roll back state that
we would otherwise expect to clean up through the event being handled by
userland and perform the memory freeing duty otherwise performed by
dup_userfaultfd_complete().
We do this by implementing a new function, dup_userfaultfd_fail(), which
performs the same loop, only decrementing reference counts.
Note that we perform mmgrab() on the parent and child mm's, however
userfaultfd_ctx_put() will mmdrop() this once the reference count drops to
zero, so we will avoid memory leaks correctly here.
Link: https://lkml.kernel.org/r/cover.1729014377.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/d3691d58bb58712b6fb3df2be441d175bd3cdf07.17290143…
Fixes: d24062914837 ("fork: use __mt_dup() to duplicate maple tree in dup_mmap()")
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com>
Reported-by: Jann Horn <jannh(a)google.com>
Reviewed-by: Jann Horn <jannh(a)google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett(a)Oracle.com>
Cc: Alexander Viro <viro(a)zeniv.linux.org.uk>
Cc: Christian Brauner <brauner(a)kernel.org>
Cc: Jan Kara <jack(a)suse.cz>
Cc: Linus Torvalds <torvalds(a)linuxfoundation.org>
Cc: Vlastimil Babka <vbabka(a)suse.cz>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
fs/userfaultfd.c | 28 ++++++++++++++++++++++++++++
include/linux/userfaultfd_k.h | 5 +++++
kernel/fork.c | 5 ++++-
3 files changed, 37 insertions(+), 1 deletion(-)
--- a/fs/userfaultfd.c~fork-do-not-invoke-uffd-on-fork-if-error-occurs
+++ a/fs/userfaultfd.c
@@ -692,6 +692,34 @@ void dup_userfaultfd_complete(struct lis
}
}
+void dup_userfaultfd_fail(struct list_head *fcs)
+{
+ struct userfaultfd_fork_ctx *fctx, *n;
+
+ /*
+ * An error has occurred on fork, we will tear memory down, but have
+ * allocated memory for fctx's and raised reference counts for both the
+ * original and child contexts (and on the mm for each as a result).
+ *
+ * These would ordinarily be taken care of by a user handling the event,
+ * but we are no longer doing so, so manually clean up here.
+ *
+ * mm tear down will take care of cleaning up VMA contexts.
+ */
+ list_for_each_entry_safe(fctx, n, fcs, list) {
+ struct userfaultfd_ctx *octx = fctx->orig;
+ struct userfaultfd_ctx *ctx = fctx->new;
+
+ atomic_dec(&octx->mmap_changing);
+ VM_BUG_ON(atomic_read(&octx->mmap_changing) < 0);
+ userfaultfd_ctx_put(octx);
+ userfaultfd_ctx_put(ctx);
+
+ list_del(&fctx->list);
+ kfree(fctx);
+ }
+}
+
void mremap_userfaultfd_prep(struct vm_area_struct *vma,
struct vm_userfaultfd_ctx *vm_ctx)
{
--- a/include/linux/userfaultfd_k.h~fork-do-not-invoke-uffd-on-fork-if-error-occurs
+++ a/include/linux/userfaultfd_k.h
@@ -249,6 +249,7 @@ static inline bool vma_can_userfault(str
extern int dup_userfaultfd(struct vm_area_struct *, struct list_head *);
extern void dup_userfaultfd_complete(struct list_head *);
+void dup_userfaultfd_fail(struct list_head *);
extern void mremap_userfaultfd_prep(struct vm_area_struct *,
struct vm_userfaultfd_ctx *);
@@ -351,6 +352,10 @@ static inline void dup_userfaultfd_compl
{
}
+static inline void dup_userfaultfd_fail(struct list_head *l)
+{
+}
+
static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
struct vm_userfaultfd_ctx *ctx)
{
--- a/kernel/fork.c~fork-do-not-invoke-uffd-on-fork-if-error-occurs
+++ a/kernel/fork.c
@@ -775,7 +775,10 @@ out:
mmap_write_unlock(mm);
flush_tlb_mm(oldmm);
mmap_write_unlock(oldmm);
- dup_userfaultfd_complete(&uf);
+ if (!retval)
+ dup_userfaultfd_complete(&uf);
+ else
+ dup_userfaultfd_fail(&uf);
fail_uprobe_end:
uprobe_end_dup_mmap();
return retval;
_
Patches currently in -mm which might be from lorenzo.stoakes(a)oracle.com are
mm-avoid-unsafe-vma-hook-invocation-when-error-arises-on-mmap-hook.patch
mm-unconditionally-close-vmas-on-error.patch
mm-refactor-map_deny_write_exec.patch
mm-resolve-faulty-mmap_region-error-path-behaviour.patch
selftests-mm-add-pkey_sighandler_xx-hugetlb_dio-to-gitignore.patch
mm-refactor-mm_access-to-not-return-null.patch
mm-refactor-mm_access-to-not-return-null-fix.patch
mm-madvise-unrestrict-process_madvise-for-current-process.patch
maple_tree-do-not-hash-pointers-on-dump-in-debug-mode.patch
tools-testing-fix-phys_addr_t-size-on-64-bit-systems.patch
tools-testing-fix-phys_addr_t-size-on-64-bit-systems-fix.patch
tools-testing-add-additional-vma_internalh-stubs.patch
mm-isolate-mmap-internal-logic-to-mm-vmac.patch
mm-refactor-__mmap_region.patch
mm-defer-second-attempt-at-merge-on-mmap.patch
mm-pagewalk-add-the-ability-to-install-ptes.patch
mm-add-pte_marker_guard-pte-marker.patch
mm-madvise-implement-lightweight-guard-page-mechanism.patch
tools-testing-update-tools-uapi-header-for-mman-commonh.patch
selftests-mm-add-self-tests-for-guard-page-feature.patch