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mm,page_owner: fix recursion 

Prior to 217b2119b9 ("mm,page_owner: implement the tracking of the
stacks count") the only place where page_owner could potentially go into
recursion due to its need of allocating more memory was in save_stack(),
which ends up calling into stackdepot code with the possibility of
allocating memory.

We made sure to guard against that by signaling that the current task was
already in page_owner code, so in case a recursion attempt was made, we
could catch that and return dummy_handle.

After above commit, a new place in page_owner code was introduced where we
could allocate memory, meaning we could go into recursion would we take
that path.

Make sure to signal that we are in page_owner in that codepath as well. 
Move the guard code into two helpers {un}set_current_in_page_owner() and
use them prior to calling in the two functions that might allocate memory.

Link: https://lkml.kernel.org/r/20240315222610.6870-1-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Fixes: 217b2119b9 ("mm,page_owner: implement the tracking of the stacks count")
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Marco Elver <elver@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Oscar Salvador 2024-03-15 23:26:10 +01:00 committed by Andrew Morton
parent 3290032466
commit 7844c01472
1 changed files with 23 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
mm/page_owner.c
View File

@ -54,6 +54,22 @@ static depot_stack_handle_t early_handle;
static void init_early_allocated_pages(void);
static inline void set_current_in_page_owner(void)
{
/*
* Avoid recursion.
*
* We might need to allocate more memory from page_owner code, so make
* sure to signal it in order to avoid recursion.
*/
current->in_page_owner = 1;
}
static inline void unset_current_in_page_owner(void)
{
current->in_page_owner = 0;
}
static int __init early_page_owner_param(char *buf)
{
int ret = kstrtobool(buf, &page_owner_enabled);
@ -133,23 +149,16 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
depot_stack_handle_t handle;
unsigned int nr_entries;
/*
* Avoid recursion.
*
* Sometimes page metadata allocation tracking requires more
* memory to be allocated:
* - when new stack trace is saved to stack depot
*/
if (current->in_page_owner)
return dummy_handle;
current->in_page_owner = 1;
set_current_in_page_owner();
nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
handle = stack_depot_save(entries, nr_entries, flags);
if (!handle)
handle = failure_handle;
unset_current_in_page_owner();
current->in_page_owner = 0;
return handle;
}
@ -164,9 +173,13 @@ static void add_stack_record_to_list(struct stack_record *stack_record,
gfp_mask &= (GFP_ATOMIC | GFP_KERNEL);
gfp_mask |= __GFP_NOWARN;
set_current_in_page_owner();
stack = kmalloc(sizeof(*stack), gfp_mask);
if (!stack)
if (!stack) {
unset_current_in_page_owner();
return;
}
unset_current_in_page_owner();
stack->stack_record = stack_record;
stack->next = NULL;