The patch titled
Subject: objpool: fix to make percpu slot allocation more robust
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
objpool-fix-to-make-percpu-slot-allocation-more-robust.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/objpool-fix-to-make-percpu-slot-allocation-more-robust.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Subject: objpool: fix to make percpu slot allocation more robust
Date: Mon, 28 Oct 2024 12:26:27 +0900
Since gfp & GFP_ATOMIC == GFP_ATOMIC is true for GFP_KERNEL | GFP_HIGH, it
will use kmalloc if user specifies that combination. Here the reason why
combining the __vmalloc_node() and kmalloc_node() is that the vmalloc does
not support all GFP flag, especially GFP_ATOMIC. So we should check if
gfp & (GFP_ATOMIC | GFP_KERNEL) != GFP_ATOMIC for vmalloc first. This
ensures caller can sleep. And for the robustness, even if vmalloc fails,
it should retry with kmalloc to allocate it.
Link: https://lkml.kernel.org/r/173008598713.1262174.2959179484209897252.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: aff1871bfc81 ("objpool: fix choosing allocation for percpu slots")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/all/CAHk-=whO+vSH+XVRio8byJU8idAWES0SPGVZ7KAVdc4qrV0VUA@xxxxxxxxxxxxxx/
Cc: Leo Yan <leo.yan@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Wu <wuqiang.matt@xxxxxxxxxxxxx>
Cc: Mikel Rychliski <mikel@xxxxxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Cc: Viktor Malik <vmalik@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/objpool.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
--- a/lib/objpool.c~objpool-fix-to-make-percpu-slot-allocation-more-robust
+++ a/lib/objpool.c
@@ -74,15 +74,21 @@ objpool_init_percpu_slots(struct objpool
* warm caches and TLB hits. in default vmalloc is used to
* reduce the pressure of kernel slab system. as we know,
* mimimal size of vmalloc is one page since vmalloc would
- * always align the requested size to page size
+ * always align the requested size to page size.
+ * but if vmalloc fails or it is not available (e.g. GFP_ATOMIC)
+ * allocate percpu slot with kmalloc.
*/
- if ((pool->gfp & GFP_ATOMIC) == GFP_ATOMIC)
- slot = kmalloc_node(size, pool->gfp, cpu_to_node(i));
- else
+ slot = NULL;
+
+ if ((pool->gfp & (GFP_ATOMIC | GFP_KERNEL)) != GFP_ATOMIC)
slot = __vmalloc_node(size, sizeof(void *), pool->gfp,
cpu_to_node(i), __builtin_return_address(0));
- if (!slot)
- return -ENOMEM;
+
+ if (!slot) {
+ slot = kmalloc_node(size, pool->gfp, cpu_to_node(i));
+ if (!slot)
+ return -ENOMEM;
+ }
memset(slot, 0, size);
pool->cpu_slots[i] = slot;
_
Patches currently in -mm which might be from mhiramat@xxxxxxxxxx are
objpool-fix-to-make-percpu-slot-allocation-more-robust.patch
