* [PATCH v6] mm/vmalloc: fix data race in show_numa_info()
@ 2025-05-08 16:56 Jeongjun Park
2025-05-08 17:48 ` Uladzislau Rezki
0 siblings, 1 reply; 7+ messages in thread
From: Jeongjun Park @ 2025-05-08 16:56 UTC (permalink / raw)
To: akpm; +Cc: urezki, edumazet, linux-mm, linux-kernel, Jeongjun Park
The following data-race was found in show_numa_info():
==================================================================
BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show
read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0:
show_numa_info mm/vmalloc.c:4936 [inline]
vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016
seq_read_iter+0x373/0xb40 fs/seq_file.c:230
proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299
....
write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1:
show_numa_info mm/vmalloc.c:4934 [inline]
vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016
seq_read_iter+0x373/0xb40 fs/seq_file.c:230
proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299
....
value changed: 0x0000008f -> 0x00000000
==================================================================
According to this report,there is a read/write data-race because m->private
is accessible to multiple CPUs. To fix this, instead of allocating the heap
in proc_vmalloc_init() and passing the heap address to m->private,
vmalloc_info_show() should allocate the heap.
Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information")
Suggested-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
---
v6: Change CONFIG_NUMA to must be check before doing any work related to the counters array.
- Link to v5: https://lore.kernel.org/all/20250508160800.12540-1-aha310510@gmail.com/
v5: Change heap to be allocated only when CONFIG_NUMA is enabled
- Link to v4: https://lore.kernel.org/all/20250508065558.149091-1-aha310510@gmail.com/
v4: Change the way counters array heap is allocated, per Andrew Morton's suggestion.
And fix it to call smp_rmb() in the correct location.
- Link to v3: https://lore.kernel.org/all/20250507142552.9446-1-aha310510@gmail.com/
v3: Following Uladzislau Rezki's suggestion, we check v->flags beforehand
to avoid printing uninitialized members of vm_struct.
- Link to v2: https://lore.kernel.org/all/20250506082520.84153-1-aha310510@gmail.com/
v2: Refactoring some functions and fix patch as per Eric Dumazet suggestion
- Link to v1: https://lore.kernel.org/all/20250505171948.24410-1-aha310510@gmail.com/
---
mm/vmalloc.c | 63 +++++++++++++++++++++++++++++-----------------------
1 file changed, 35 insertions(+), 28 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 3ed720a787ec..c1ea9713a1c0 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm)
/*
* Before removing VM_UNINITIALIZED,
* we should make sure that vm has proper values.
- * Pair with smp_rmb() in show_numa_info().
+ * Pair with smp_rmb() in vread_iter() and vmalloc_info_show().
*/
smp_wmb();
vm->flags &= ~VM_UNINITIALIZED;
@@ -4914,28 +4914,29 @@ bool vmalloc_dump_obj(void *object)
#endif
#ifdef CONFIG_PROC_FS
-static void show_numa_info(struct seq_file *m, struct vm_struct *v)
-{
- if (IS_ENABLED(CONFIG_NUMA)) {
- unsigned int nr, *counters = m->private;
- unsigned int step = 1U << vm_area_page_order(v);
- if (!counters)
- return;
+/*
+ * Print number of pages allocated on each memory node.
+ *
+ * This function can only be called if CONFIG_NUMA is enabled
+ * and VM_UNINITIALIZED bit in v->flags is disabled.
+ */
+static void show_numa_info(struct seq_file *m, struct vm_struct *v,
+ unsigned int *counters)
+{
+ unsigned int nr;
+ unsigned int step = 1U << vm_area_page_order(v);
- if (v->flags & VM_UNINITIALIZED)
- return;
- /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
- smp_rmb();
+ if (!counters)
+ return;
- memset(counters, 0, nr_node_ids * sizeof(unsigned int));
+ memset(counters, 0, nr_node_ids * sizeof(unsigned int));
- for (nr = 0; nr < v->nr_pages; nr += step)
- counters[page_to_nid(v->pages[nr])] += step;
- for_each_node_state(nr, N_HIGH_MEMORY)
- if (counters[nr])
- seq_printf(m, " N%u=%u", nr, counters[nr]);
- }
+ for (nr = 0; nr < v->nr_pages; nr += step)
+ counters[page_to_nid(v->pages[nr])] += step;
+ for_each_node_state(nr, N_HIGH_MEMORY)
+ if (counters[nr])
+ seq_printf(m, " N%u=%u", nr, counters[nr]);
}
static void show_purge_info(struct seq_file *m)
@@ -4962,8 +4963,12 @@ static int vmalloc_info_show(struct seq_file *m, void *p)
struct vmap_node *vn;
struct vmap_area *va;
struct vm_struct *v;
+ unsigned int *counters;
int i;
+ if (IS_ENABLED(CONFIG_NUMA))
+ counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL);
+
for (i = 0; i < nr_vmap_nodes; i++) {
vn = &vmap_nodes[i];
@@ -4979,6 +4984,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p)
}
v = va->vm;
+ if (v->flags & VM_UNINITIALIZED)
+ continue;
+
+ /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
+ smp_rmb();
seq_printf(m, "0x%pK-0x%pK %7ld",
v->addr, v->addr + v->size, v->size);
@@ -5013,7 +5023,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p)
if (is_vmalloc_addr(v->pages))
seq_puts(m, " vpages");
- show_numa_info(m, v);
+ if (IS_ENABLED(CONFIG_NUMA))
+ show_numa_info(m, v, counters);
+
seq_putc(m, '\n');
}
spin_unlock(&vn->busy.lock);
@@ -5023,19 +5035,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p)
* As a final step, dump "unpurged" areas.
*/
show_purge_info(m);
+ if (IS_ENABLED(CONFIG_NUMA))
+ kfree(counters);
return 0;
}
static int __init proc_vmalloc_init(void)
{
- void *priv_data = NULL;
-
- if (IS_ENABLED(CONFIG_NUMA))
- priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL);
-
- proc_create_single_data("vmallocinfo",
- 0400, NULL, vmalloc_info_show, priv_data);
-
+ proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show);
return 0;
}
module_init(proc_vmalloc_init);
--
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH v6] mm/vmalloc: fix data race in show_numa_info() 2025-05-08 16:56 [PATCH v6] mm/vmalloc: fix data race in show_numa_info() Jeongjun Park @ 2025-05-08 17:48 ` Uladzislau Rezki 2025-05-08 18:02 ` Uladzislau Rezki 0 siblings, 1 reply; 7+ messages in thread From: Uladzislau Rezki @ 2025-05-08 17:48 UTC (permalink / raw) To: Jeongjun Park; +Cc: akpm, urezki, edumazet, linux-mm, linux-kernel On Fri, May 09, 2025 at 01:56:20AM +0900, Jeongjun Park wrote: > The following data-race was found in show_numa_info(): > > ================================================================== > BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show > > read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: > show_numa_info mm/vmalloc.c:4936 [inline] > vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > .... > > write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: > show_numa_info mm/vmalloc.c:4934 [inline] > vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > .... > > value changed: 0x0000008f -> 0x00000000 > ================================================================== > > According to this report,there is a read/write data-race because m->private > is accessible to multiple CPUs. To fix this, instead of allocating the heap > in proc_vmalloc_init() and passing the heap address to m->private, > vmalloc_info_show() should allocate the heap. > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > Suggested-by: Eric Dumazet <edumazet@google.com> > Suggested-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Jeongjun Park <aha310510@gmail.com> > --- > v6: Change CONFIG_NUMA to must be check before doing any work related to the counters array. > - Link to v5: https://lore.kernel.org/all/20250508160800.12540-1-aha310510@gmail.com/ > v5: Change heap to be allocated only when CONFIG_NUMA is enabled > - Link to v4: https://lore.kernel.org/all/20250508065558.149091-1-aha310510@gmail.com/ > v4: Change the way counters array heap is allocated, per Andrew Morton's suggestion. > And fix it to call smp_rmb() in the correct location. > - Link to v3: https://lore.kernel.org/all/20250507142552.9446-1-aha310510@gmail.com/ > v3: Following Uladzislau Rezki's suggestion, we check v->flags beforehand > to avoid printing uninitialized members of vm_struct. > - Link to v2: https://lore.kernel.org/all/20250506082520.84153-1-aha310510@gmail.com/ > v2: Refactoring some functions and fix patch as per Eric Dumazet suggestion > - Link to v1: https://lore.kernel.org/all/20250505171948.24410-1-aha310510@gmail.com/ > --- > mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- > 1 file changed, 35 insertions(+), 28 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 3ed720a787ec..c1ea9713a1c0 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm) > /* > * Before removing VM_UNINITIALIZED, > * we should make sure that vm has proper values. > - * Pair with smp_rmb() in show_numa_info(). > + * Pair with smp_rmb() in vread_iter() and vmalloc_info_show(). > */ > smp_wmb(); > vm->flags &= ~VM_UNINITIALIZED; > @@ -4914,28 +4914,29 @@ bool vmalloc_dump_obj(void *object) > #endif > > #ifdef CONFIG_PROC_FS > -static void show_numa_info(struct seq_file *m, struct vm_struct *v) > -{ > - if (IS_ENABLED(CONFIG_NUMA)) { > - unsigned int nr, *counters = m->private; > - unsigned int step = 1U << vm_area_page_order(v); > > - if (!counters) > - return; > +/* > + * Print number of pages allocated on each memory node. > + * > + * This function can only be called if CONFIG_NUMA is enabled > + * and VM_UNINITIALIZED bit in v->flags is disabled. > + */ > +static void show_numa_info(struct seq_file *m, struct vm_struct *v, > + unsigned int *counters) > +{ > + unsigned int nr; > + unsigned int step = 1U << vm_area_page_order(v); > > - if (v->flags & VM_UNINITIALIZED) > - return; > - /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > - smp_rmb(); > + if (!counters) > + return; > > - memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > - for (nr = 0; nr < v->nr_pages; nr += step) > - counters[page_to_nid(v->pages[nr])] += step; > - for_each_node_state(nr, N_HIGH_MEMORY) > - if (counters[nr]) > - seq_printf(m, " N%u=%u", nr, counters[nr]); > - } > + for (nr = 0; nr < v->nr_pages; nr += step) > + counters[page_to_nid(v->pages[nr])] += step; > + for_each_node_state(nr, N_HIGH_MEMORY) > + if (counters[nr]) > + seq_printf(m, " N%u=%u", nr, counters[nr]); > } > > static void show_purge_info(struct seq_file *m) > @@ -4962,8 +4963,12 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > struct vmap_node *vn; > struct vmap_area *va; > struct vm_struct *v; > + unsigned int *counters; > int i; > > + if (IS_ENABLED(CONFIG_NUMA)) > + counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > + > for (i = 0; i < nr_vmap_nodes; i++) { > vn = &vmap_nodes[i]; > > @@ -4979,6 +4984,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > } > > v = va->vm; > + if (v->flags & VM_UNINITIALIZED) > + continue; > + > + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > + smp_rmb(); > > seq_printf(m, "0x%pK-0x%pK %7ld", > v->addr, v->addr + v->size, v->size); > @@ -5013,7 +5023,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > if (is_vmalloc_addr(v->pages)) > seq_puts(m, " vpages"); > > - show_numa_info(m, v); > + if (IS_ENABLED(CONFIG_NUMA)) > + show_numa_info(m, v, counters); > + > seq_putc(m, '\n'); > } > spin_unlock(&vn->busy.lock); > @@ -5023,19 +5035,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > * As a final step, dump "unpurged" areas. > */ > show_purge_info(m); > + if (IS_ENABLED(CONFIG_NUMA)) > + kfree(counters); > return 0; > } > > static int __init proc_vmalloc_init(void) > { > - void *priv_data = NULL; > - > - if (IS_ENABLED(CONFIG_NUMA)) > - priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > - > - proc_create_single_data("vmallocinfo", > - 0400, NULL, vmalloc_info_show, priv_data); > - > + proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show); > return 0; > } > module_init(proc_vmalloc_init); > -- LGTM: Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com> Thank you! -- Uladzislau Rezki ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v6] mm/vmalloc: fix data race in show_numa_info() 2025-05-08 17:48 ` Uladzislau Rezki @ 2025-05-08 18:02 ` Uladzislau Rezki 2025-07-01 16:01 ` Jeongjun Park 0 siblings, 1 reply; 7+ messages in thread From: Uladzislau Rezki @ 2025-05-08 18:02 UTC (permalink / raw) To: Jeongjun Park; +Cc: Jeongjun Park, akpm, edumazet, linux-mm, linux-kernel On Thu, May 08, 2025 at 07:48:55PM +0200, Uladzislau Rezki wrote: > On Fri, May 09, 2025 at 01:56:20AM +0900, Jeongjun Park wrote: > > The following data-race was found in show_numa_info(): > > > > ================================================================== > > BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show > > > > read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: > > show_numa_info mm/vmalloc.c:4936 [inline] > > vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > .... > > > > write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: > > show_numa_info mm/vmalloc.c:4934 [inline] > > vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > .... > > > > value changed: 0x0000008f -> 0x00000000 > > ================================================================== > > > > According to this report,there is a read/write data-race because m->private > > is accessible to multiple CPUs. To fix this, instead of allocating the heap > > in proc_vmalloc_init() and passing the heap address to m->private, > > vmalloc_info_show() should allocate the heap. > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > Suggested-by: Eric Dumazet <edumazet@google.com> > > Suggested-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > Signed-off-by: Jeongjun Park <aha310510@gmail.com> > > --- > > v6: Change CONFIG_NUMA to must be check before doing any work related to the counters array. > > - Link to v5: https://lore.kernel.org/all/20250508160800.12540-1-aha310510@gmail.com/ > > v5: Change heap to be allocated only when CONFIG_NUMA is enabled > > - Link to v4: https://lore.kernel.org/all/20250508065558.149091-1-aha310510@gmail.com/ > > v4: Change the way counters array heap is allocated, per Andrew Morton's suggestion. > > And fix it to call smp_rmb() in the correct location. > > - Link to v3: https://lore.kernel.org/all/20250507142552.9446-1-aha310510@gmail.com/ > > v3: Following Uladzislau Rezki's suggestion, we check v->flags beforehand > > to avoid printing uninitialized members of vm_struct. > > - Link to v2: https://lore.kernel.org/all/20250506082520.84153-1-aha310510@gmail.com/ > > v2: Refactoring some functions and fix patch as per Eric Dumazet suggestion > > - Link to v1: https://lore.kernel.org/all/20250505171948.24410-1-aha310510@gmail.com/ > > --- > > mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- > > 1 file changed, 35 insertions(+), 28 deletions(-) > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index 3ed720a787ec..c1ea9713a1c0 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm) > > /* > > * Before removing VM_UNINITIALIZED, > > * we should make sure that vm has proper values. > > - * Pair with smp_rmb() in show_numa_info(). > > + * Pair with smp_rmb() in vread_iter() and vmalloc_info_show(). > > */ > > smp_wmb(); > > vm->flags &= ~VM_UNINITIALIZED; > > @@ -4914,28 +4914,29 @@ bool vmalloc_dump_obj(void *object) > > #endif > > > > #ifdef CONFIG_PROC_FS > > -static void show_numa_info(struct seq_file *m, struct vm_struct *v) > > -{ > > - if (IS_ENABLED(CONFIG_NUMA)) { > > - unsigned int nr, *counters = m->private; > > - unsigned int step = 1U << vm_area_page_order(v); > > > > - if (!counters) > > - return; > > +/* > > + * Print number of pages allocated on each memory node. > > + * > > + * This function can only be called if CONFIG_NUMA is enabled > > + * and VM_UNINITIALIZED bit in v->flags is disabled. > > + */ > > +static void show_numa_info(struct seq_file *m, struct vm_struct *v, > > + unsigned int *counters) > > +{ > > + unsigned int nr; > > + unsigned int step = 1U << vm_area_page_order(v); > > > > - if (v->flags & VM_UNINITIALIZED) > > - return; > > - /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > - smp_rmb(); > > + if (!counters) > > + return; > > > > - memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > - for (nr = 0; nr < v->nr_pages; nr += step) > > - counters[page_to_nid(v->pages[nr])] += step; > > - for_each_node_state(nr, N_HIGH_MEMORY) > > - if (counters[nr]) > > - seq_printf(m, " N%u=%u", nr, counters[nr]); > > - } > > + for (nr = 0; nr < v->nr_pages; nr += step) > > + counters[page_to_nid(v->pages[nr])] += step; > > + for_each_node_state(nr, N_HIGH_MEMORY) > > + if (counters[nr]) > > + seq_printf(m, " N%u=%u", nr, counters[nr]); > > } > > > > static void show_purge_info(struct seq_file *m) > > @@ -4962,8 +4963,12 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > struct vmap_node *vn; > > struct vmap_area *va; > > struct vm_struct *v; > > + unsigned int *counters; > > int i; > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > + counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > + > > for (i = 0; i < nr_vmap_nodes; i++) { > > vn = &vmap_nodes[i]; > > > > @@ -4979,6 +4984,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > } > > > > v = va->vm; > > + if (v->flags & VM_UNINITIALIZED) > > + continue; > > + > > + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > + smp_rmb(); > > > > seq_printf(m, "0x%pK-0x%pK %7ld", > > v->addr, v->addr + v->size, v->size); > > @@ -5013,7 +5023,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > if (is_vmalloc_addr(v->pages)) > > seq_puts(m, " vpages"); > > > > - show_numa_info(m, v); > > + if (IS_ENABLED(CONFIG_NUMA)) > > + show_numa_info(m, v, counters); > > + > > seq_putc(m, '\n'); > > } > > spin_unlock(&vn->busy.lock); > > @@ -5023,19 +5035,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > * As a final step, dump "unpurged" areas. > > */ > > show_purge_info(m); > > + if (IS_ENABLED(CONFIG_NUMA)) > > + kfree(counters); > > return 0; > > } > > > > static int __init proc_vmalloc_init(void) > > { > > - void *priv_data = NULL; > > - > > - if (IS_ENABLED(CONFIG_NUMA)) > > - priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > - > > - proc_create_single_data("vmallocinfo", > > - 0400, NULL, vmalloc_info_show, priv_data); > > - > > + proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show); > > return 0; > > } > > module_init(proc_vmalloc_init); > > -- > LGTM: > > Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com> > > Thank you! > Also one thing i have just noticed. The "Fixes tag" should be updated to this: Fixes: 8e1d743f2c26 ("mm: vmalloc: support multiple nodes in vmallocinfo") the below one should not be blamed: Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") Thanks! -- Uladzislau Rezki ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v6] mm/vmalloc: fix data race in show_numa_info() 2025-05-08 18:02 ` Uladzislau Rezki @ 2025-07-01 16:01 ` Jeongjun Park 2025-07-02 11:40 ` Uladzislau Rezki 0 siblings, 1 reply; 7+ messages in thread From: Jeongjun Park @ 2025-07-01 16:01 UTC (permalink / raw) To: Uladzislau Rezki; +Cc: akpm, edumazet, linux-mm, linux-kernel Uladzislau Rezki <urezki@gmail.com> wrote: > > On Thu, May 08, 2025 at 07:48:55PM +0200, Uladzislau Rezki wrote: > > On Fri, May 09, 2025 at 01:56:20AM +0900, Jeongjun Park wrote: > > > The following data-race was found in show_numa_info(): > > > > > > ================================================================== > > > BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show > > > > > > read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: > > > show_numa_info mm/vmalloc.c:4936 [inline] > > > vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > .... > > > > > > write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: > > > show_numa_info mm/vmalloc.c:4934 [inline] > > > vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > .... > > > > > > value changed: 0x0000008f -> 0x00000000 > > > ================================================================== > > > > > > According to this report,there is a read/write data-race because m->private > > > is accessible to multiple CPUs. To fix this, instead of allocating the heap > > > in proc_vmalloc_init() and passing the heap address to m->private, > > > vmalloc_info_show() should allocate the heap. > > > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > > Suggested-by: Eric Dumazet <edumazet@google.com> > > > Suggested-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > > Signed-off-by: Jeongjun Park <aha310510@gmail.com> > > > --- > > > v6: Change CONFIG_NUMA to must be check before doing any work related to the counters array. > > > - Link to v5: https://lore.kernel.org/all/20250508160800.12540-1-aha310510@gmail.com/ > > > v5: Change heap to be allocated only when CONFIG_NUMA is enabled > > > - Link to v4: https://lore.kernel.org/all/20250508065558.149091-1-aha310510@gmail.com/ > > > v4: Change the way counters array heap is allocated, per Andrew Morton's suggestion. > > > And fix it to call smp_rmb() in the correct location. > > > - Link to v3: https://lore.kernel.org/all/20250507142552.9446-1-aha310510@gmail.com/ > > > v3: Following Uladzislau Rezki's suggestion, we check v->flags beforehand > > > to avoid printing uninitialized members of vm_struct. > > > - Link to v2: https://lore.kernel.org/all/20250506082520.84153-1-aha310510@gmail.com/ > > > v2: Refactoring some functions and fix patch as per Eric Dumazet suggestion > > > - Link to v1: https://lore.kernel.org/all/20250505171948.24410-1-aha310510@gmail.com/ > > > --- > > > mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- > > > 1 file changed, 35 insertions(+), 28 deletions(-) > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > index 3ed720a787ec..c1ea9713a1c0 100644 > > > --- a/mm/vmalloc.c > > > +++ b/mm/vmalloc.c > > > @@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm) > > > /* > > > * Before removing VM_UNINITIALIZED, > > > * we should make sure that vm has proper values. > > > - * Pair with smp_rmb() in show_numa_info(). > > > + * Pair with smp_rmb() in vread_iter() and vmalloc_info_show(). > > > */ > > > smp_wmb(); > > > vm->flags &= ~VM_UNINITIALIZED; > > > @@ -4914,28 +4914,29 @@ bool vmalloc_dump_obj(void *object) > > > #endif > > > > > > #ifdef CONFIG_PROC_FS > > > -static void show_numa_info(struct seq_file *m, struct vm_struct *v) > > > -{ > > > - if (IS_ENABLED(CONFIG_NUMA)) { > > > - unsigned int nr, *counters = m->private; > > > - unsigned int step = 1U << vm_area_page_order(v); > > > > > > - if (!counters) > > > - return; > > > +/* > > > + * Print number of pages allocated on each memory node. > > > + * > > > + * This function can only be called if CONFIG_NUMA is enabled > > > + * and VM_UNINITIALIZED bit in v->flags is disabled. > > > + */ > > > +static void show_numa_info(struct seq_file *m, struct vm_struct *v, > > > + unsigned int *counters) > > > +{ > > > + unsigned int nr; > > > + unsigned int step = 1U << vm_area_page_order(v); > > > > > > - if (v->flags & VM_UNINITIALIZED) > > > - return; > > > - /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > - smp_rmb(); > > > + if (!counters) > > > + return; > > > > > > - memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > > > - for (nr = 0; nr < v->nr_pages; nr += step) > > > - counters[page_to_nid(v->pages[nr])] += step; > > > - for_each_node_state(nr, N_HIGH_MEMORY) > > > - if (counters[nr]) > > > - seq_printf(m, " N%u=%u", nr, counters[nr]); > > > - } > > > + for (nr = 0; nr < v->nr_pages; nr += step) > > > + counters[page_to_nid(v->pages[nr])] += step; > > > + for_each_node_state(nr, N_HIGH_MEMORY) > > > + if (counters[nr]) > > > + seq_printf(m, " N%u=%u", nr, counters[nr]); > > > } > > > > > > static void show_purge_info(struct seq_file *m) > > > @@ -4962,8 +4963,12 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > struct vmap_node *vn; > > > struct vmap_area *va; > > > struct vm_struct *v; > > > + unsigned int *counters; > > > int i; > > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > + counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > + > > > for (i = 0; i < nr_vmap_nodes; i++) { > > > vn = &vmap_nodes[i]; > > > > > > @@ -4979,6 +4984,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > } > > > > > > v = va->vm; > > > + if (v->flags & VM_UNINITIALIZED) > > > + continue; > > > + > > > + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > + smp_rmb(); > > > > > > seq_printf(m, "0x%pK-0x%pK %7ld", > > > v->addr, v->addr + v->size, v->size); > > > @@ -5013,7 +5023,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > if (is_vmalloc_addr(v->pages)) > > > seq_puts(m, " vpages"); > > > > > > - show_numa_info(m, v); > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > + show_numa_info(m, v, counters); > > > + > > > seq_putc(m, '\n'); > > > } > > > spin_unlock(&vn->busy.lock); > > > @@ -5023,19 +5035,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > * As a final step, dump "unpurged" areas. > > > */ > > > show_purge_info(m); > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > + kfree(counters); > > > return 0; > > > } > > > > > > static int __init proc_vmalloc_init(void) > > > { > > > - void *priv_data = NULL; > > > - > > > - if (IS_ENABLED(CONFIG_NUMA)) > > > - priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > - > > > - proc_create_single_data("vmallocinfo", > > > - 0400, NULL, vmalloc_info_show, priv_data); > > > - > > > + proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show); > > > return 0; > > > } > > > module_init(proc_vmalloc_init); > > > -- > > LGTM: > > > > Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com> > > > > Thank you! > > > Also one thing i have just noticed. The "Fixes tag" should be updated to > this: Fixes: 8e1d743f2c26 ("mm: vmalloc: support multiple nodes in vmallocinfo") > > the below one should not be blamed: > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > Thanks! > > -- > Uladzislau Rezki I've been looking through the stable tree and it seems like this issue still exists in the stable tree, so I think this patch needs to be backported. What do you think? Regards, Jeongjun Park ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v6] mm/vmalloc: fix data race in show_numa_info() 2025-07-01 16:01 ` Jeongjun Park @ 2025-07-02 11:40 ` Uladzislau Rezki 2025-07-02 14:01 ` Jeongjun Park 0 siblings, 1 reply; 7+ messages in thread From: Uladzislau Rezki @ 2025-07-02 11:40 UTC (permalink / raw) To: Jeongjun Park; +Cc: Uladzislau Rezki, akpm, edumazet, linux-mm, linux-kernel On Wed, Jul 02, 2025 at 01:01:13AM +0900, Jeongjun Park wrote: > Uladzislau Rezki <urezki@gmail.com> wrote: > > > > On Thu, May 08, 2025 at 07:48:55PM +0200, Uladzislau Rezki wrote: > > > On Fri, May 09, 2025 at 01:56:20AM +0900, Jeongjun Park wrote: > > > > The following data-race was found in show_numa_info(): > > > > > > > > ================================================================== > > > > BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show > > > > > > > > read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: > > > > show_numa_info mm/vmalloc.c:4936 [inline] > > > > vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 > > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > > .... > > > > > > > > write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: > > > > show_numa_info mm/vmalloc.c:4934 [inline] > > > > vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 > > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > > .... > > > > > > > > value changed: 0x0000008f -> 0x00000000 > > > > ================================================================== > > > > > > > > According to this report,there is a read/write data-race because m->private > > > > is accessible to multiple CPUs. To fix this, instead of allocating the heap > > > > in proc_vmalloc_init() and passing the heap address to m->private, > > > > vmalloc_info_show() should allocate the heap. > > > > > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > > > Suggested-by: Eric Dumazet <edumazet@google.com> > > > > Suggested-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > > > Signed-off-by: Jeongjun Park <aha310510@gmail.com> > > > > --- > > > > v6: Change CONFIG_NUMA to must be check before doing any work related to the counters array. > > > > - Link to v5: https://lore.kernel.org/all/20250508160800.12540-1-aha310510@gmail.com/ > > > > v5: Change heap to be allocated only when CONFIG_NUMA is enabled > > > > - Link to v4: https://lore.kernel.org/all/20250508065558.149091-1-aha310510@gmail.com/ > > > > v4: Change the way counters array heap is allocated, per Andrew Morton's suggestion. > > > > And fix it to call smp_rmb() in the correct location. > > > > - Link to v3: https://lore.kernel.org/all/20250507142552.9446-1-aha310510@gmail.com/ > > > > v3: Following Uladzislau Rezki's suggestion, we check v->flags beforehand > > > > to avoid printing uninitialized members of vm_struct. > > > > - Link to v2: https://lore.kernel.org/all/20250506082520.84153-1-aha310510@gmail.com/ > > > > v2: Refactoring some functions and fix patch as per Eric Dumazet suggestion > > > > - Link to v1: https://lore.kernel.org/all/20250505171948.24410-1-aha310510@gmail.com/ > > > > --- > > > > mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- > > > > 1 file changed, 35 insertions(+), 28 deletions(-) > > > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > > index 3ed720a787ec..c1ea9713a1c0 100644 > > > > --- a/mm/vmalloc.c > > > > +++ b/mm/vmalloc.c > > > > @@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm) > > > > /* > > > > * Before removing VM_UNINITIALIZED, > > > > * we should make sure that vm has proper values. > > > > - * Pair with smp_rmb() in show_numa_info(). > > > > + * Pair with smp_rmb() in vread_iter() and vmalloc_info_show(). > > > > */ > > > > smp_wmb(); > > > > vm->flags &= ~VM_UNINITIALIZED; > > > > @@ -4914,28 +4914,29 @@ bool vmalloc_dump_obj(void *object) > > > > #endif > > > > > > > > #ifdef CONFIG_PROC_FS > > > > -static void show_numa_info(struct seq_file *m, struct vm_struct *v) > > > > -{ > > > > - if (IS_ENABLED(CONFIG_NUMA)) { > > > > - unsigned int nr, *counters = m->private; > > > > - unsigned int step = 1U << vm_area_page_order(v); > > > > > > > > - if (!counters) > > > > - return; > > > > +/* > > > > + * Print number of pages allocated on each memory node. > > > > + * > > > > + * This function can only be called if CONFIG_NUMA is enabled > > > > + * and VM_UNINITIALIZED bit in v->flags is disabled. > > > > + */ > > > > +static void show_numa_info(struct seq_file *m, struct vm_struct *v, > > > > + unsigned int *counters) > > > > +{ > > > > + unsigned int nr; > > > > + unsigned int step = 1U << vm_area_page_order(v); > > > > > > > > - if (v->flags & VM_UNINITIALIZED) > > > > - return; > > > > - /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > > - smp_rmb(); > > > > + if (!counters) > > > > + return; > > > > > > > > - memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > > > > > - for (nr = 0; nr < v->nr_pages; nr += step) > > > > - counters[page_to_nid(v->pages[nr])] += step; > > > > - for_each_node_state(nr, N_HIGH_MEMORY) > > > > - if (counters[nr]) > > > > - seq_printf(m, " N%u=%u", nr, counters[nr]); > > > > - } > > > > + for (nr = 0; nr < v->nr_pages; nr += step) > > > > + counters[page_to_nid(v->pages[nr])] += step; > > > > + for_each_node_state(nr, N_HIGH_MEMORY) > > > > + if (counters[nr]) > > > > + seq_printf(m, " N%u=%u", nr, counters[nr]); > > > > } > > > > > > > > static void show_purge_info(struct seq_file *m) > > > > @@ -4962,8 +4963,12 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > struct vmap_node *vn; > > > > struct vmap_area *va; > > > > struct vm_struct *v; > > > > + unsigned int *counters; > > > > int i; > > > > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > + counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > > + > > > > for (i = 0; i < nr_vmap_nodes; i++) { > > > > vn = &vmap_nodes[i]; > > > > > > > > @@ -4979,6 +4984,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > } > > > > > > > > v = va->vm; > > > > + if (v->flags & VM_UNINITIALIZED) > > > > + continue; > > > > + > > > > + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > > + smp_rmb(); > > > > > > > > seq_printf(m, "0x%pK-0x%pK %7ld", > > > > v->addr, v->addr + v->size, v->size); > > > > @@ -5013,7 +5023,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > if (is_vmalloc_addr(v->pages)) > > > > seq_puts(m, " vpages"); > > > > > > > > - show_numa_info(m, v); > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > + show_numa_info(m, v, counters); > > > > + > > > > seq_putc(m, '\n'); > > > > } > > > > spin_unlock(&vn->busy.lock); > > > > @@ -5023,19 +5035,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > * As a final step, dump "unpurged" areas. > > > > */ > > > > show_purge_info(m); > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > + kfree(counters); > > > > return 0; > > > > } > > > > > > > > static int __init proc_vmalloc_init(void) > > > > { > > > > - void *priv_data = NULL; > > > > - > > > > - if (IS_ENABLED(CONFIG_NUMA)) > > > > - priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > > - > > > > - proc_create_single_data("vmallocinfo", > > > > - 0400, NULL, vmalloc_info_show, priv_data); > > > > - > > > > + proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show); > > > > return 0; > > > > } > > > > module_init(proc_vmalloc_init); > > > > -- > > > LGTM: > > > > > > Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com> > > > > > > Thank you! > > > > > Also one thing i have just noticed. The "Fixes tag" should be updated to > > this: Fixes: 8e1d743f2c26 ("mm: vmalloc: support multiple nodes in vmallocinfo") > > > > the below one should not be blamed: > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > > > Thanks! > > > > -- > > Uladzislau Rezki > > I've been looking through the stable tree and it seems like this issue > still exists in the stable tree, so I think this patch needs to be > backported. > > What do you think? > If the stable does not have it, we should backport it. But it has to be done only for those where a vmap-node logic is in place. It was delivered starting from the v6.9 kernel version. -- Uladzislau Rezki ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v6] mm/vmalloc: fix data race in show_numa_info() 2025-07-02 11:40 ` Uladzislau Rezki @ 2025-07-02 14:01 ` Jeongjun Park 2025-07-02 15:00 ` Uladzislau Rezki 0 siblings, 1 reply; 7+ messages in thread From: Jeongjun Park @ 2025-07-02 14:01 UTC (permalink / raw) To: Uladzislau Rezki; +Cc: akpm, edumazet, linux-mm, linux-kernel Uladzislau Rezki <urezki@gmail.com> wrote: > > On Wed, Jul 02, 2025 at 01:01:13AM +0900, Jeongjun Park wrote: > > Uladzislau Rezki <urezki@gmail.com> wrote: > > > > > > On Thu, May 08, 2025 at 07:48:55PM +0200, Uladzislau Rezki wrote: > > > > On Fri, May 09, 2025 at 01:56:20AM +0900, Jeongjun Park wrote: > > > > > The following data-race was found in show_numa_info(): > > > > > > > > > > ================================================================== > > > > > BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show > > > > > > > > > > read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: > > > > > show_numa_info mm/vmalloc.c:4936 [inline] > > > > > vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 > > > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > > > .... > > > > > > > > > > write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: > > > > > show_numa_info mm/vmalloc.c:4934 [inline] > > > > > vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 > > > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > > > .... > > > > > > > > > > value changed: 0x0000008f -> 0x00000000 > > > > > ================================================================== > > > > > > > > > > According to this report,there is a read/write data-race because m->private > > > > > is accessible to multiple CPUs. To fix this, instead of allocating the heap > > > > > in proc_vmalloc_init() and passing the heap address to m->private, > > > > > vmalloc_info_show() should allocate the heap. > > > > > > > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > > > > Suggested-by: Eric Dumazet <edumazet@google.com> > > > > > Suggested-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > > > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > > > > Signed-off-by: Jeongjun Park <aha310510@gmail.com> > > > > > --- > > > > > v6: Change CONFIG_NUMA to must be check before doing any work related to the counters array. > > > > > - Link to v5: https://lore.kernel.org/all/20250508160800.12540-1-aha310510@gmail.com/ > > > > > v5: Change heap to be allocated only when CONFIG_NUMA is enabled > > > > > - Link to v4: https://lore.kernel.org/all/20250508065558.149091-1-aha310510@gmail.com/ > > > > > v4: Change the way counters array heap is allocated, per Andrew Morton's suggestion. > > > > > And fix it to call smp_rmb() in the correct location. > > > > > - Link to v3: https://lore.kernel.org/all/20250507142552.9446-1-aha310510@gmail.com/ > > > > > v3: Following Uladzislau Rezki's suggestion, we check v->flags beforehand > > > > > to avoid printing uninitialized members of vm_struct. > > > > > - Link to v2: https://lore.kernel.org/all/20250506082520.84153-1-aha310510@gmail.com/ > > > > > v2: Refactoring some functions and fix patch as per Eric Dumazet suggestion > > > > > - Link to v1: https://lore.kernel.org/all/20250505171948.24410-1-aha310510@gmail.com/ > > > > > --- > > > > > mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- > > > > > 1 file changed, 35 insertions(+), 28 deletions(-) > > > > > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > > > index 3ed720a787ec..c1ea9713a1c0 100644 > > > > > --- a/mm/vmalloc.c > > > > > +++ b/mm/vmalloc.c > > > > > @@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm) > > > > > /* > > > > > * Before removing VM_UNINITIALIZED, > > > > > * we should make sure that vm has proper values. > > > > > - * Pair with smp_rmb() in show_numa_info(). > > > > > + * Pair with smp_rmb() in vread_iter() and vmalloc_info_show(). > > > > > */ > > > > > smp_wmb(); > > > > > vm->flags &= ~VM_UNINITIALIZED; > > > > > @@ -4914,28 +4914,29 @@ bool vmalloc_dump_obj(void *object) > > > > > #endif > > > > > > > > > > #ifdef CONFIG_PROC_FS > > > > > -static void show_numa_info(struct seq_file *m, struct vm_struct *v) > > > > > -{ > > > > > - if (IS_ENABLED(CONFIG_NUMA)) { > > > > > - unsigned int nr, *counters = m->private; > > > > > - unsigned int step = 1U << vm_area_page_order(v); > > > > > > > > > > - if (!counters) > > > > > - return; > > > > > +/* > > > > > + * Print number of pages allocated on each memory node. > > > > > + * > > > > > + * This function can only be called if CONFIG_NUMA is enabled > > > > > + * and VM_UNINITIALIZED bit in v->flags is disabled. > > > > > + */ > > > > > +static void show_numa_info(struct seq_file *m, struct vm_struct *v, > > > > > + unsigned int *counters) > > > > > +{ > > > > > + unsigned int nr; > > > > > + unsigned int step = 1U << vm_area_page_order(v); > > > > > > > > > > - if (v->flags & VM_UNINITIALIZED) > > > > > - return; > > > > > - /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > > > - smp_rmb(); > > > > > + if (!counters) > > > > > + return; > > > > > > > > > > - memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > > + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > > > > > > > - for (nr = 0; nr < v->nr_pages; nr += step) > > > > > - counters[page_to_nid(v->pages[nr])] += step; > > > > > - for_each_node_state(nr, N_HIGH_MEMORY) > > > > > - if (counters[nr]) > > > > > - seq_printf(m, " N%u=%u", nr, counters[nr]); > > > > > - } > > > > > + for (nr = 0; nr < v->nr_pages; nr += step) > > > > > + counters[page_to_nid(v->pages[nr])] += step; > > > > > + for_each_node_state(nr, N_HIGH_MEMORY) > > > > > + if (counters[nr]) > > > > > + seq_printf(m, " N%u=%u", nr, counters[nr]); > > > > > } > > > > > > > > > > static void show_purge_info(struct seq_file *m) > > > > > @@ -4962,8 +4963,12 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > struct vmap_node *vn; > > > > > struct vmap_area *va; > > > > > struct vm_struct *v; > > > > > + unsigned int *counters; > > > > > int i; > > > > > > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > > + counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > > > + > > > > > for (i = 0; i < nr_vmap_nodes; i++) { > > > > > vn = &vmap_nodes[i]; > > > > > > > > > > @@ -4979,6 +4984,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > } > > > > > > > > > > v = va->vm; > > > > > + if (v->flags & VM_UNINITIALIZED) > > > > > + continue; > > > > > + > > > > > + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > > > + smp_rmb(); > > > > > > > > > > seq_printf(m, "0x%pK-0x%pK %7ld", > > > > > v->addr, v->addr + v->size, v->size); > > > > > @@ -5013,7 +5023,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > if (is_vmalloc_addr(v->pages)) > > > > > seq_puts(m, " vpages"); > > > > > > > > > > - show_numa_info(m, v); > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > > + show_numa_info(m, v, counters); > > > > > + > > > > > seq_putc(m, '\n'); > > > > > } > > > > > spin_unlock(&vn->busy.lock); > > > > > @@ -5023,19 +5035,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > * As a final step, dump "unpurged" areas. > > > > > */ > > > > > show_purge_info(m); > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > > + kfree(counters); > > > > > return 0; > > > > > } > > > > > > > > > > static int __init proc_vmalloc_init(void) > > > > > { > > > > > - void *priv_data = NULL; > > > > > - > > > > > - if (IS_ENABLED(CONFIG_NUMA)) > > > > > - priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > > > - > > > > > - proc_create_single_data("vmallocinfo", > > > > > - 0400, NULL, vmalloc_info_show, priv_data); > > > > > - > > > > > + proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show); > > > > > return 0; > > > > > } > > > > > module_init(proc_vmalloc_init); > > > > > -- > > > > LGTM: > > > > > > > > Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com> > > > > > > > > Thank you! > > > > > > > Also one thing i have just noticed. The "Fixes tag" should be updated to > > > this: Fixes: 8e1d743f2c26 ("mm: vmalloc: support multiple nodes in vmallocinfo") > > > > > > the below one should not be blamed: > > > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > > > > > Thanks! > > > > > > -- > > > Uladzislau Rezki > > > > I've been looking through the stable tree and it seems like this issue > > still exists in the stable tree, so I think this patch needs to be > > backported. > > > > What do you think? > > > If the stable does not have it, we should backport it. But it has to be > done only for those where a vmap-node logic is in place. It was delivered > starting from the v6.9 kernel version. > Then I guess I should backport to 6.12, 6.15. Thanks for letting me know! Regards, Jeongjun Park ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v6] mm/vmalloc: fix data race in show_numa_info() 2025-07-02 14:01 ` Jeongjun Park @ 2025-07-02 15:00 ` Uladzislau Rezki 0 siblings, 0 replies; 7+ messages in thread From: Uladzislau Rezki @ 2025-07-02 15:00 UTC (permalink / raw) To: Jeongjun Park; +Cc: Uladzislau Rezki, akpm, edumazet, linux-mm, linux-kernel On Wed, Jul 02, 2025 at 11:01:23PM +0900, Jeongjun Park wrote: > Uladzislau Rezki <urezki@gmail.com> wrote: > > > > On Wed, Jul 02, 2025 at 01:01:13AM +0900, Jeongjun Park wrote: > > > Uladzislau Rezki <urezki@gmail.com> wrote: > > > > > > > > On Thu, May 08, 2025 at 07:48:55PM +0200, Uladzislau Rezki wrote: > > > > > On Fri, May 09, 2025 at 01:56:20AM +0900, Jeongjun Park wrote: > > > > > > The following data-race was found in show_numa_info(): > > > > > > > > > > > > ================================================================== > > > > > > BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show > > > > > > > > > > > > read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: > > > > > > show_numa_info mm/vmalloc.c:4936 [inline] > > > > > > vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 > > > > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > > > > .... > > > > > > > > > > > > write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: > > > > > > show_numa_info mm/vmalloc.c:4934 [inline] > > > > > > vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 > > > > > > seq_read_iter+0x373/0xb40 fs/seq_file.c:230 > > > > > > proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 > > > > > > .... > > > > > > > > > > > > value changed: 0x0000008f -> 0x00000000 > > > > > > ================================================================== > > > > > > > > > > > > According to this report,there is a read/write data-race because m->private > > > > > > is accessible to multiple CPUs. To fix this, instead of allocating the heap > > > > > > in proc_vmalloc_init() and passing the heap address to m->private, > > > > > > vmalloc_info_show() should allocate the heap. > > > > > > > > > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > > > > > Suggested-by: Eric Dumazet <edumazet@google.com> > > > > > > Suggested-by: Uladzislau Rezki (Sony) <urezki@gmail.com> > > > > > > Suggested-by: Andrew Morton <akpm@linux-foundation.org> > > > > > > Signed-off-by: Jeongjun Park <aha310510@gmail.com> > > > > > > --- > > > > > > v6: Change CONFIG_NUMA to must be check before doing any work related to the counters array. > > > > > > - Link to v5: https://lore.kernel.org/all/20250508160800.12540-1-aha310510@gmail.com/ > > > > > > v5: Change heap to be allocated only when CONFIG_NUMA is enabled > > > > > > - Link to v4: https://lore.kernel.org/all/20250508065558.149091-1-aha310510@gmail.com/ > > > > > > v4: Change the way counters array heap is allocated, per Andrew Morton's suggestion. > > > > > > And fix it to call smp_rmb() in the correct location. > > > > > > - Link to v3: https://lore.kernel.org/all/20250507142552.9446-1-aha310510@gmail.com/ > > > > > > v3: Following Uladzislau Rezki's suggestion, we check v->flags beforehand > > > > > > to avoid printing uninitialized members of vm_struct. > > > > > > - Link to v2: https://lore.kernel.org/all/20250506082520.84153-1-aha310510@gmail.com/ > > > > > > v2: Refactoring some functions and fix patch as per Eric Dumazet suggestion > > > > > > - Link to v1: https://lore.kernel.org/all/20250505171948.24410-1-aha310510@gmail.com/ > > > > > > --- > > > > > > mm/vmalloc.c | 63 +++++++++++++++++++++++++++++----------------------- > > > > > > 1 file changed, 35 insertions(+), 28 deletions(-) > > > > > > > > > > > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > > > > > index 3ed720a787ec..c1ea9713a1c0 100644 > > > > > > --- a/mm/vmalloc.c > > > > > > +++ b/mm/vmalloc.c > > > > > > @@ -3100,7 +3100,7 @@ static void clear_vm_uninitialized_flag(struct vm_struct *vm) > > > > > > /* > > > > > > * Before removing VM_UNINITIALIZED, > > > > > > * we should make sure that vm has proper values. > > > > > > - * Pair with smp_rmb() in show_numa_info(). > > > > > > + * Pair with smp_rmb() in vread_iter() and vmalloc_info_show(). > > > > > > */ > > > > > > smp_wmb(); > > > > > > vm->flags &= ~VM_UNINITIALIZED; > > > > > > @@ -4914,28 +4914,29 @@ bool vmalloc_dump_obj(void *object) > > > > > > #endif > > > > > > > > > > > > #ifdef CONFIG_PROC_FS > > > > > > -static void show_numa_info(struct seq_file *m, struct vm_struct *v) > > > > > > -{ > > > > > > - if (IS_ENABLED(CONFIG_NUMA)) { > > > > > > - unsigned int nr, *counters = m->private; > > > > > > - unsigned int step = 1U << vm_area_page_order(v); > > > > > > > > > > > > - if (!counters) > > > > > > - return; > > > > > > +/* > > > > > > + * Print number of pages allocated on each memory node. > > > > > > + * > > > > > > + * This function can only be called if CONFIG_NUMA is enabled > > > > > > + * and VM_UNINITIALIZED bit in v->flags is disabled. > > > > > > + */ > > > > > > +static void show_numa_info(struct seq_file *m, struct vm_struct *v, > > > > > > + unsigned int *counters) > > > > > > +{ > > > > > > + unsigned int nr; > > > > > > + unsigned int step = 1U << vm_area_page_order(v); > > > > > > > > > > > > - if (v->flags & VM_UNINITIALIZED) > > > > > > - return; > > > > > > - /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > > > > - smp_rmb(); > > > > > > + if (!counters) > > > > > > + return; > > > > > > > > > > > > - memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > > > + memset(counters, 0, nr_node_ids * sizeof(unsigned int)); > > > > > > > > > > > > - for (nr = 0; nr < v->nr_pages; nr += step) > > > > > > - counters[page_to_nid(v->pages[nr])] += step; > > > > > > - for_each_node_state(nr, N_HIGH_MEMORY) > > > > > > - if (counters[nr]) > > > > > > - seq_printf(m, " N%u=%u", nr, counters[nr]); > > > > > > - } > > > > > > + for (nr = 0; nr < v->nr_pages; nr += step) > > > > > > + counters[page_to_nid(v->pages[nr])] += step; > > > > > > + for_each_node_state(nr, N_HIGH_MEMORY) > > > > > > + if (counters[nr]) > > > > > > + seq_printf(m, " N%u=%u", nr, counters[nr]); > > > > > > } > > > > > > > > > > > > static void show_purge_info(struct seq_file *m) > > > > > > @@ -4962,8 +4963,12 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > > struct vmap_node *vn; > > > > > > struct vmap_area *va; > > > > > > struct vm_struct *v; > > > > > > + unsigned int *counters; > > > > > > int i; > > > > > > > > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > > > + counters = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > > > > + > > > > > > for (i = 0; i < nr_vmap_nodes; i++) { > > > > > > vn = &vmap_nodes[i]; > > > > > > > > > > > > @@ -4979,6 +4984,11 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > > } > > > > > > > > > > > > v = va->vm; > > > > > > + if (v->flags & VM_UNINITIALIZED) > > > > > > + continue; > > > > > > + > > > > > > + /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */ > > > > > > + smp_rmb(); > > > > > > > > > > > > seq_printf(m, "0x%pK-0x%pK %7ld", > > > > > > v->addr, v->addr + v->size, v->size); > > > > > > @@ -5013,7 +5023,9 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > > if (is_vmalloc_addr(v->pages)) > > > > > > seq_puts(m, " vpages"); > > > > > > > > > > > > - show_numa_info(m, v); > > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > > > + show_numa_info(m, v, counters); > > > > > > + > > > > > > seq_putc(m, '\n'); > > > > > > } > > > > > > spin_unlock(&vn->busy.lock); > > > > > > @@ -5023,19 +5035,14 @@ static int vmalloc_info_show(struct seq_file *m, void *p) > > > > > > * As a final step, dump "unpurged" areas. > > > > > > */ > > > > > > show_purge_info(m); > > > > > > + if (IS_ENABLED(CONFIG_NUMA)) > > > > > > + kfree(counters); > > > > > > return 0; > > > > > > } > > > > > > > > > > > > static int __init proc_vmalloc_init(void) > > > > > > { > > > > > > - void *priv_data = NULL; > > > > > > - > > > > > > - if (IS_ENABLED(CONFIG_NUMA)) > > > > > > - priv_data = kmalloc(nr_node_ids * sizeof(unsigned int), GFP_KERNEL); > > > > > > - > > > > > > - proc_create_single_data("vmallocinfo", > > > > > > - 0400, NULL, vmalloc_info_show, priv_data); > > > > > > - > > > > > > + proc_create_single("vmallocinfo", 0400, NULL, vmalloc_info_show); > > > > > > return 0; > > > > > > } > > > > > > module_init(proc_vmalloc_init); > > > > > > -- > > > > > LGTM: > > > > > > > > > > Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com> > > > > > > > > > > Thank you! > > > > > > > > > Also one thing i have just noticed. The "Fixes tag" should be updated to > > > > this: Fixes: 8e1d743f2c26 ("mm: vmalloc: support multiple nodes in vmallocinfo") > > > > > > > > the below one should not be blamed: > > > > > > > > Fixes: a47a126ad5ea ("vmallocinfo: add NUMA information") > > > > > > > > Thanks! > > > > > > > > -- > > > > Uladzislau Rezki > > > > > > I've been looking through the stable tree and it seems like this issue > > > still exists in the stable tree, so I think this patch needs to be > > > backported. > > > > > > What do you think? > > > > > If the stable does not have it, we should backport it. But it has to be > > done only for those where a vmap-node logic is in place. It was delivered > > starting from the v6.9 kernel version. > > > > Then I guess I should backport to 6.12, 6.15. Thanks for letting me know! > You are welcome! -- Uladzislau Rezki ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2025-07-02 15:01 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2025-05-08 16:56 [PATCH v6] mm/vmalloc: fix data race in show_numa_info() Jeongjun Park 2025-05-08 17:48 ` Uladzislau Rezki 2025-05-08 18:02 ` Uladzislau Rezki 2025-07-01 16:01 ` Jeongjun Park 2025-07-02 11:40 ` Uladzislau Rezki 2025-07-02 14:01 ` Jeongjun Park 2025-07-02 15:00 ` Uladzislau Rezki
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