* + mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch added to mm-unstable branch
@ 2025-01-12 5:46 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2025-01-12 5:46 UTC (permalink / raw)
To: mm-commits, willy, vbabka, souravpanda, shakeel.butt,
richard.weiyang, peterz, peterx, paulmck, pasha.tatashin,
oliver.sang, oleg, mjguzik, minchan, mhocko, mgorman,
lorenzo.stoakes, lokeshgidra, Liam.Howlett, klarasmodin, jannh,
hughd, hdanton, hannes, dhowells, david, dave, corbet, brauner,
surenb, akpm
The patch titled
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
has been added to the -mm mm-unstable branch. Its filename is
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Suren Baghdasaryan <surenb@google.com>
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
Date: Fri, 10 Jan 2025 20:25:54 -0800
With upcoming replacement of vm_lock with vm_refcnt, we need to handle a
possibility of vma_start_read_locked/vma_start_read_locked_nested failing
due to refcount overflow. Prepare for such possibility by changing these
APIs and adjusting their users.
Link: https://lkml.kernel.org/r/20250111042604.3230628-8-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Mattew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/mm.h | 6 ++++--
mm/userfaultfd.c | 18 +++++++++++++-----
2 files changed, 17 insertions(+), 7 deletions(-)
--- a/include/linux/mm.h~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/include/linux/mm.h
@@ -747,10 +747,11 @@ static inline bool vma_start_read(struct
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
+static inline bool vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
{
mmap_assert_locked(vma->vm_mm);
down_read_nested(&vma->vm_lock.lock, subclass);
+ return true;
}
/*
@@ -759,10 +760,11 @@ static inline void vma_start_read_locked
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked(struct vm_area_struct *vma)
+static inline bool vma_start_read_locked(struct vm_area_struct *vma)
{
mmap_assert_locked(vma->vm_mm);
down_read(&vma->vm_lock.lock);
+ return true;
}
static inline void vma_end_read(struct vm_area_struct *vma)
--- a/mm/userfaultfd.c~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/mm/userfaultfd.c
@@ -85,7 +85,8 @@ static struct vm_area_struct *uffd_lock_
mmap_read_lock(mm);
vma = find_vma_and_prepare_anon(mm, address);
if (!IS_ERR(vma))
- vma_start_read_locked(vma);
+ if (!vma_start_read_locked(vma))
+ vma = ERR_PTR(-EAGAIN);
mmap_read_unlock(mm);
return vma;
@@ -1483,10 +1484,17 @@ static int uffd_move_lock(struct mm_stru
mmap_read_lock(mm);
err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap);
if (!err) {
- vma_start_read_locked(*dst_vmap);
- if (*dst_vmap != *src_vmap)
- vma_start_read_locked_nested(*src_vmap,
- SINGLE_DEPTH_NESTING);
+ if (vma_start_read_locked(*dst_vmap)) {
+ if (*dst_vmap != *src_vmap) {
+ if (!vma_start_read_locked_nested(*src_vmap,
+ SINGLE_DEPTH_NESTING)) {
+ vma_end_read(*dst_vmap);
+ err = -EAGAIN;
+ }
+ }
+ } else {
+ err = -EAGAIN;
+ }
}
mmap_read_unlock(mm);
return err;
_
Patches currently in -mm which might be from surenb@google.com are
alloc_tag-skip-pgalloc_tag_swap-if-profiling-is-disabled.patch
tools-fix-atomic_set-definition-to-set-the-value-correctly.patch
seqlock-add-raw_seqcount_try_begin.patch
mm-convert-mm_lock_seq-to-a-proper-seqcount.patch
mm-introduce-mmap_lock_speculate_try_beginretry.patch
mm-introduce-vma_start_read_locked_nested-helpers.patch
mm-move-per-vma-lock-into-vm_area_struct.patch
mm-mark-vma-as-detached-until-its-added-into-vma-tree.patch
mm-introduce-vma_iter_store_attached-to-use-with-attached-vmas.patch
mm-mark-vmas-detached-upon-exit.patch
types-move-struct-rcuwait-into-typesh.patch
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
mm-move-mmap_init_lock-out-of-the-header-file.patch
mm-uninline-the-main-body-of-vma_start_write.patch
refcount-introduce-__refcount_addinc_not_zero_limited.patch
mm-replace-vm_lock-and-detached-flag-with-a-reference-count.patch
mm-move-lesser-used-vma_area_struct-members-into-the-last-cacheline.patch
mm-debug-print-vm_refcnt-state-when-dumping-the-vma.patch
mm-remove-extra-vma_numab_state_init-call.patch
mm-prepare-lock_vma_under_rcu-for-vma-reuse-possibility.patch
mm-make-vma-cache-slab_typesafe_by_rcu.patch
docs-mm-document-latest-changes-to-vm_lock.patch
alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled.patch
^ permalink raw reply [flat|nested] 4+ messages in thread* + mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch added to mm-unstable branch
@ 2025-02-15 0:42 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2025-02-15 0:42 UTC (permalink / raw)
To: mm-commits, willy, will, vbabka, souravpanda, shivankg,
shakeel.butt, richard.weiyang, peterz, peterx, paulmck,
pasha.tatashin, oleg, mjguzik, minchan, mhocko, mgorman,
lorenzo.stoakes, lokeshgidra, Liam.Howlett, klarasmodin, jannh,
hughd, hdanton, hannes, dhowells, david, dave, corbet, brauner,
surenb, akpm
The patch titled
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
has been added to the -mm mm-unstable branch. Its filename is
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Suren Baghdasaryan <surenb@google.com>
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
Date: Thu, 13 Feb 2025 14:46:44 -0800
With upcoming replacement of vm_lock with vm_refcnt, we need to handle a
possibility of vma_start_read_locked/vma_start_read_locked_nested failing
due to refcount overflow. Prepare for such possibility by changing these
APIs and adjusting their users.
Link: https://lkml.kernel.org/r/20250213224655.1680278-8-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickens <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/mm.h | 6 ++++--
mm/userfaultfd.c | 30 +++++++++++++++++++++++-------
2 files changed, 27 insertions(+), 9 deletions(-)
--- a/include/linux/mm.h~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/include/linux/mm.h
@@ -747,10 +747,11 @@ static inline bool vma_start_read(struct
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
+static inline bool vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
{
mmap_assert_locked(vma->vm_mm);
down_read_nested(&vma->vm_lock.lock, subclass);
+ return true;
}
/*
@@ -759,10 +760,11 @@ static inline void vma_start_read_locked
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked(struct vm_area_struct *vma)
+static inline bool vma_start_read_locked(struct vm_area_struct *vma)
{
mmap_assert_locked(vma->vm_mm);
down_read(&vma->vm_lock.lock);
+ return true;
}
static inline void vma_end_read(struct vm_area_struct *vma)
--- a/mm/userfaultfd.c~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/mm/userfaultfd.c
@@ -84,8 +84,12 @@ static struct vm_area_struct *uffd_lock_
mmap_read_lock(mm);
vma = find_vma_and_prepare_anon(mm, address);
- if (!IS_ERR(vma))
- vma_start_read_locked(vma);
+ if (!IS_ERR(vma)) {
+ bool locked = vma_start_read_locked(vma);
+
+ if (!locked)
+ vma = ERR_PTR(-EAGAIN);
+ }
mmap_read_unlock(mm);
return vma;
@@ -1482,12 +1486,24 @@ static int uffd_move_lock(struct mm_stru
mmap_read_lock(mm);
err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap);
- if (!err) {
- vma_start_read_locked(*dst_vmap);
- if (*dst_vmap != *src_vmap)
- vma_start_read_locked_nested(*src_vmap,
- SINGLE_DEPTH_NESTING);
+ if (err)
+ goto out;
+
+ if (!vma_start_read_locked(*dst_vmap)) {
+ err = -EAGAIN;
+ goto out;
}
+
+ /* Nothing further to do if both vmas are locked. */
+ if (*dst_vmap == *src_vmap)
+ goto out;
+
+ if (!vma_start_read_locked_nested(*src_vmap, SINGLE_DEPTH_NESTING)) {
+ /* Undo dst_vmap locking if src_vmap failed to lock */
+ vma_end_read(*dst_vmap);
+ err = -EAGAIN;
+ }
+out:
mmap_read_unlock(mm);
return err;
}
_
Patches currently in -mm which might be from surenb@google.com are
alloc_tag-work-around-clang-14-issue-with-__builtin_object_size.patch
mm-avoid-extra-mem_alloc_profiling_enabled-checks.patch
alloc_tag-uninline-code-gated-by-mem_alloc_profiling_key-in-slab-allocator.patch
alloc_tag-uninline-code-gated-by-mem_alloc_profiling_key-in-page-allocator.patch
mm-introduce-vma_start_read_locked_nested-helpers.patch
mm-move-per-vma-lock-into-vm_area_struct.patch
mm-mark-vma-as-detached-until-its-added-into-vma-tree.patch
mm-introduce-vma_iter_store_attached-to-use-with-attached-vmas.patch
mm-mark-vmas-detached-upon-exit.patch
types-move-struct-rcuwait-into-typesh.patch
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
mm-move-mmap_init_lock-out-of-the-header-file.patch
mm-uninline-the-main-body-of-vma_start_write.patch
refcount-provide-ops-for-cases-when-objects-memory-can-be-reused.patch
refcount-introduce-__refcount_addinc_not_zero_limited_acquire.patch
mm-replace-vm_lock-and-detached-flag-with-a-reference-count.patch
mm-move-lesser-used-vma_area_struct-members-into-the-last-cacheline.patch
mm-debug-print-vm_refcnt-state-when-dumping-the-vma.patch
mm-remove-extra-vma_numab_state_init-call.patch
mm-prepare-lock_vma_under_rcu-for-vma-reuse-possibility.patch
mm-make-vma-cache-slab_typesafe_by_rcu.patch
docs-mm-document-latest-changes-to-vm_lock.patch
^ permalink raw reply [flat|nested] 4+ messages in thread* + mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch added to mm-unstable branch
@ 2025-01-09 5:44 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2025-01-09 5:44 UTC (permalink / raw)
To: mm-commits, willy, vbabka, souravpanda, shakeel.butt,
richard.weiyang, peterz, peterx, paulmck, pasha.tatashin, oleg,
mjguzik, minchan, mhocko, mgorman, lorenzo.stoakes, lokeshgidra,
Liam.Howlett, klarasmodin, jannh, hughd, hdanton, hannes,
dhowells, david, dave, corbet, brauner, surenb, akpm
The patch titled
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
has been added to the -mm mm-unstable branch. Its filename is
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Suren Baghdasaryan <surenb@google.com>
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
Date: Wed, 8 Jan 2025 18:30:16 -0800
With upcoming replacement of vm_lock with vm_refcnt, we need to handle a
possibility of vma_start_read_locked/vma_start_read_locked_nested failing
due to refcount overflow. Prepare for such possibility by changing these
APIs and adjusting their users.
Link: https://lkml.kernel.org/r/20250109023025.2242447-8-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/mm.h | 6 ++++--
mm/userfaultfd.c | 18 +++++++++++++-----
2 files changed, 17 insertions(+), 7 deletions(-)
--- a/include/linux/mm.h~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/include/linux/mm.h
@@ -747,10 +747,11 @@ static inline bool vma_start_read(struct
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
+static inline bool vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
{
mmap_assert_locked(vma->vm_mm);
down_read_nested(&vma->vm_lock.lock, subclass);
+ return true;
}
/*
@@ -759,10 +760,11 @@ static inline void vma_start_read_locked
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked(struct vm_area_struct *vma)
+static inline bool vma_start_read_locked(struct vm_area_struct *vma)
{
mmap_assert_locked(vma->vm_mm);
down_read(&vma->vm_lock.lock);
+ return true;
}
static inline void vma_end_read(struct vm_area_struct *vma)
--- a/mm/userfaultfd.c~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/mm/userfaultfd.c
@@ -85,7 +85,8 @@ static struct vm_area_struct *uffd_lock_
mmap_read_lock(mm);
vma = find_vma_and_prepare_anon(mm, address);
if (!IS_ERR(vma))
- vma_start_read_locked(vma);
+ if (!vma_start_read_locked(vma))
+ vma = ERR_PTR(-EAGAIN);
mmap_read_unlock(mm);
return vma;
@@ -1483,10 +1484,17 @@ static int uffd_move_lock(struct mm_stru
mmap_read_lock(mm);
err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap);
if (!err) {
- vma_start_read_locked(*dst_vmap);
- if (*dst_vmap != *src_vmap)
- vma_start_read_locked_nested(*src_vmap,
- SINGLE_DEPTH_NESTING);
+ if (vma_start_read_locked(*dst_vmap)) {
+ if (*dst_vmap != *src_vmap) {
+ if (!vma_start_read_locked_nested(*src_vmap,
+ SINGLE_DEPTH_NESTING)) {
+ vma_end_read(*dst_vmap);
+ err = -EAGAIN;
+ }
+ }
+ } else {
+ err = -EAGAIN;
+ }
}
mmap_read_unlock(mm);
return err;
_
Patches currently in -mm which might be from surenb@google.com are
alloc_tag-skip-pgalloc_tag_swap-if-profiling-is-disabled.patch
tools-fix-atomic_set-definition-to-set-the-value-correctly.patch
seqlock-add-raw_seqcount_try_begin.patch
mm-convert-mm_lock_seq-to-a-proper-seqcount.patch
mm-introduce-mmap_lock_speculate_try_beginretry.patch
mm-introduce-vma_start_read_locked_nested-helpers.patch
mm-move-per-vma-lock-into-vm_area_struct.patch
mm-mark-vma-as-detached-until-its-added-into-vma-tree.patch
mm-introduce-vma_iter_store_attached-to-use-with-attached-vmas.patch
mm-mark-vmas-detached-upon-exit.patch
types-move-struct-rcuwait-into-typesh.patch
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
mm-move-mmap_init_lock-out-of-the-header-file.patch
mm-uninline-the-main-body-of-vma_start_write.patch
refcount-introduce-__refcount_addinc_not_zero_limited.patch
mm-replace-vm_lock-and-detached-flag-with-a-reference-count.patch
mm-debug-print-vm_refcnt-state-when-dumping-the-vma.patch
mm-remove-extra-vma_numab_state_init-call.patch
mm-prepare-lock_vma_under_rcu-for-vma-reuse-possibility.patch
mm-make-vma-cache-slab_typesafe_by_rcu.patch
docs-mm-document-latest-changes-to-vm_lock.patch
alloc_tag-avoid-current-alloc_tag-manipulations-when-profiling-is-disabled.patch
^ permalink raw reply [flat|nested] 4+ messages in thread* + mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch added to mm-unstable branch
@ 2024-12-26 21:16 Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2024-12-26 21:16 UTC (permalink / raw)
To: mm-commits, willy, vbabka, souravpanda, shakeel.butt, peterz,
peterx, paulmck, pasha.tatashin, oliver.sang, oleg, mjguzik,
minchan, mhocko, mgorman, lorenzo.stoakes, lokeshgidra,
Liam.Howlett, klarasmodin, jannh, hughd, hdanton, hannes,
dhowells, david, dave, corbet, brauner, surenb, akpm
The patch titled
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
has been added to the -mm mm-unstable branch. Its filename is
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Suren Baghdasaryan <surenb@google.com>
Subject: mm: allow vma_start_read_locked/vma_start_read_locked_nested to fail
Date: Thu, 26 Dec 2024 09:07:00 -0800
With upcoming replacement of vm_lock with vm_refcnt, we need to handle a
possibility of vma_start_read_locked/vma_start_read_locked_nested failing
due to refcount overflow. Prepare for such possibility by changing these
APIs and adjusting their users.
Link: https://lkml.kernel.org/r/20241226170710.1159679-9-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: kernel test robot <oliver.sang@intel.com>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/mm.h | 6 ++++--
mm/userfaultfd.c | 17 ++++++++++++-----
2 files changed, 16 insertions(+), 7 deletions(-)
--- a/include/linux/mm.h~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/include/linux/mm.h
@@ -747,10 +747,11 @@ static inline bool vma_start_read(struct
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
+static inline bool vma_start_read_locked_nested(struct vm_area_struct *vma, int subclass)
{
mmap_assert_locked(vma->vm_mm);
down_read_nested(&vma->vm_lock.lock, subclass);
+ return true;
}
/*
@@ -759,10 +760,11 @@ static inline void vma_start_read_locked
* not be used in such cases because it might fail due to mm_lock_seq overflow.
* This functionality is used to obtain vma read lock and drop the mmap read lock.
*/
-static inline void vma_start_read_locked(struct vm_area_struct *vma)
+static inline bool vma_start_read_locked(struct vm_area_struct *vma)
{
mmap_assert_locked(vma->vm_mm);
down_read(&vma->vm_lock.lock);
+ return true;
}
static inline void vma_end_read(struct vm_area_struct *vma)
--- a/mm/userfaultfd.c~mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail
+++ a/mm/userfaultfd.c
@@ -85,7 +85,8 @@ static struct vm_area_struct *uffd_lock_
mmap_read_lock(mm);
vma = find_vma_and_prepare_anon(mm, address);
if (!IS_ERR(vma))
- vma_start_read_locked(vma);
+ if (!vma_start_read_locked(vma))
+ vma = ERR_PTR(-EAGAIN);
mmap_read_unlock(mm);
return vma;
@@ -1483,10 +1484,16 @@ static int uffd_move_lock(struct mm_stru
mmap_read_lock(mm);
err = find_vmas_mm_locked(mm, dst_start, src_start, dst_vmap, src_vmap);
if (!err) {
- vma_start_read_locked(*dst_vmap);
- if (*dst_vmap != *src_vmap)
- vma_start_read_locked_nested(*src_vmap,
- SINGLE_DEPTH_NESTING);
+ if (vma_start_read_locked(*dst_vmap)) {
+ if (*dst_vmap != *src_vmap) {
+ if (!vma_start_read_locked_nested(*src_vmap,
+ SINGLE_DEPTH_NESTING)) {
+ vma_end_read(*dst_vmap);
+ err = -EAGAIN;
+ }
+ }
+ } else
+ err = -EAGAIN;
}
mmap_read_unlock(mm);
return err;
_
Patches currently in -mm which might be from surenb@google.com are
seqlock-add-raw_seqcount_try_begin.patch
mm-convert-mm_lock_seq-to-a-proper-seqcount.patch
mm-introduce-mmap_lock_speculate_try_beginretry.patch
mm-introduce-vma_start_read_locked_nested-helpers.patch
mm-move-per-vma-lock-into-vm_area_struct.patch
mm-mark-vma-as-detached-until-its-added-into-vma-tree.patch
mm-modify-vma_iter_store_gfp-to-indicate-if-its-storing-a-new-vma.patch
mm-mark-vmas-detached-upon-exit.patch
mm-nommu-fix-the-last-places-where-vma-is-not-locked-before-being-attached.patch
types-move-struct-rcuwait-into-typesh.patch
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
mm-move-mmap_init_lock-out-of-the-header-file.patch
mm-uninline-the-main-body-of-vma_start_write.patch
refcount-introduce-__refcount_addinc_not_zero_limited.patch
mm-replace-vm_lock-and-detached-flag-with-a-reference-count.patch
mm-debug-print-vm_refcnt-state-when-dumping-the-vma.patch
mm-debug-print-vm_refcnt-state-when-dumping-the-vma-fix.patch
mm-remove-extra-vma_numab_state_init-call.patch
mm-prepare-lock_vma_under_rcu-for-vma-reuse-possibility.patch
mm-make-vma-cache-slab_typesafe_by_rcu.patch
docs-mm-document-latest-changes-to-vm_lock.patch
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2025-02-15 0:42 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
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2025-02-15 0:42 Andrew Morton
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