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From: Hao Li To: "Vlastimil Babka (SUSE)" Cc: Harry Yoo , Christoph Lameter , David Rientjes , Roman Gushchin , Suren Baghdasaryan , Alexei Starovoitov , Andrew Morton , Johannes Weiner , Michal Hocko , Shakeel Butt , Alexander Potapenko , Marco Elver , Dmitry Vyukov , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Subject: Re: [PATCH v2 11/16] mm/slab: allow kmem_cache_alloc_bulk() with any gfp flags Message-ID: References: <20260610-slab_alloc_flags-v2-0-7190909db118@kernel.org> <20260610-slab_alloc_flags-v2-11-7190909db118@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260610-slab_alloc_flags-v2-11-7190909db118@kernel.org> X-Migadu-Flow: FLOW_OUT On Wed, Jun 10, 2026 at 05:40:13PM +0200, Vlastimil Babka (SUSE) wrote: > The last user of gfpflags_allow_spinning() in slab is > alloc_from_pcs_bulk(), which is only called from > kmem_cache_alloc_bulk(). > > It turns out that gfpflags_allow_spinning() is not necessary, because > kmem_cache_alloc_bulk() is only expected to be called from context that > does allow spinning, so simply replace it with 'true'. > > With that, we can remove the "@flags must allow spinning" part of the > kernel doc, as there is no more connection to the gfp flags in the slab > implementation. > > Also remove a comment in alloc_slab_obj_exts() because there should be > no more false positives possible due to gfp_allowed_mask during early > boot. > > Signed-off-by: Vlastimil Babka (SUSE) > --- > mm/slub.c | 11 ++--------- > 1 file changed, 2 insertions(+), 9 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 0b9974bfcb24..ef457e07db83 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2171,12 +2171,6 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s, > > sz = obj_exts_alloc_size(s, slab, gfp); > > - /* > - * Note that allow_spin may be false during early boot and its > - * restricted GFP_BOOT_MASK. Due to kmalloc_nolock() only supporting > - * architectures with cmpxchg16b, early obj_exts will be missing for > - * very early allocations on those. > - */ > if (unlikely(!allow_spin)) > vec = kmalloc_nolock(sz, __GFP_ZERO | __GFP_NO_OBJ_EXT, > slab_nid(slab)); > @@ -4867,7 +4861,7 @@ unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, gfp_t gfp, size_t size, > } > > full = barn_replace_empty_sheaf(barn, pcs->main, > - gfpflags_allow_spinning(gfp)); > + /* allow_spin = */ true); we can remove the `gfp` arg as this function no longer use it. > > if (full) { > stat(s, BARN_GET); > @@ -7333,8 +7327,7 @@ static bool __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, > * Allocate @size objects from @s and places them into @p. @size must be larger > * than 0. > * > - * Interrupts must be enabled when calling this function and @flags must allow > - * spinning. > + * Interrupts must be enabled when calling this function. > * > * Unlike alloc_pages_bulk(), this function does not check for already allocated > * objects in @p, and thus the caller does not need to zero it. > > -- > 2.54.0 >