+ mm-show_mem-add-trylock-while-printing-alloc-info.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/show_mem: add trylock while printing alloc info
has been added to the -mm mm-new branch.  Its filename is
     mm-show_mem-add-trylock-while-printing-alloc-info.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-show_mem-add-trylock-while-printing-alloc-info.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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------------------------------------------------------
From: Yueyang Pan <pyyjason@gmail.com>
Subject: mm/show_mem: add trylock while printing alloc info
Date: Tue, 2 Sep 2025 08:57:51 -0700

In production, show_mem() can be called concurrently from two different
entities, for example one from oom_kill_process() another from
__alloc_pages_slowpath from another kthread.  This patch adds a spinlock
and invokes trylock before printing out the kernel alloc info in
show_mem().  This way two alloc info won't interleave with each other,
which then makes parsing easier.

Link: https://lkml.kernel.org/r/1491df0ac12a7626b7c9b00e26a6e10adb8c9045.1756827906.git.pyyjason@gmail.com
Signed-off-by: Yueyang Pan <pyyjason@gmail.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Usama Arif <usamaarif642@gmail.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/show_mem.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/mm/show_mem.c~mm-show_mem-add-trylock-while-printing-alloc-info
+++ a/mm/show_mem.c
@@ -400,6 +400,7 @@ static void show_free_areas(unsigned int
 
 void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
 {
+	static DEFINE_SPINLOCK(mem_alloc_profiling_spinlock);
 	unsigned long total = 0, reserved = 0, highmem = 0;
 	struct zone *zone;
 
@@ -425,7 +426,7 @@ void __show_mem(unsigned int filter, nod
 	printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
 #endif
 #ifdef CONFIG_MEM_ALLOC_PROFILING
-	{
+	if (spin_trylock(&mem_alloc_profiling_spinlock)) {
 		struct codetag_bytes tags[10];
 		size_t i, nr;
 
@@ -453,6 +454,7 @@ void __show_mem(unsigned int filter, nod
 						  ct->lineno, ct->function);
 			}
 		}
+		spin_unlock(&mem_alloc_profiling_spinlock);
 	}
 #endif
 }
_

Patches currently in -mm which might be from pyyjason@gmail.com are

mm-damon-paddr-move-filters-existence-check-function-to-ops-common.patch
mm-damon-vaddr-support-stat-purpose-damos-filters.patch
mm-show_mem-dump-the-status-of-the-mem-alloc-profiling-before-printing.patch
mm-show_mem-add-trylock-while-printing-alloc-info.patch