Re: [PATCH 2/3] mm: avoid slub allocation while holding list_lock

From: Kirill A. Shutemov
Date: Wed Sep 11 2019 - 20:44:10 EST

On Wed, Sep 11, 2019 at 06:29:28PM -0600, Yu Zhao wrote:
> If we are already under list_lock, don't call kmalloc(). Otherwise we
> will run into deadlock because kmalloc() also tries to grab the same
> lock.
> Instead, statically allocate bitmap in struct kmem_cache_node. Given
> currently page->objects has 15 bits, we bloat the per-node struct by
> 4K. So we waste some memory but only do so when slub debug is on.

Why not have single page total protected by a lock?

Listing object from two pages at the same time doesn't make sense anyway.
Cuncurent validating is not something sane to do.

Kirill A. Shutemov