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mm/huge_memory: move THP gfp limit helper into header

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Shmem has some special requirements for THP GFP and has to limit it in
certain zones or provide a more lenient fallback.

We'll use this helper for generic swap THP allocation, which needs to
support shmem.  For a typical GFP_HIGHUSER_MOVABLE swap-in, this helper is
basically a no-op.  But it's necessary for certain shmem users, mostly
drivers.

No feature change.

Link: https://lore.kernel.org/20260517-swap-table-p4-v5-3-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kairui Song 2026-05-17 23:39:42 +08:00 committed by Andrew Morton
parent bebee474c1
commit 1dfbe92e70
2 changed files with 33 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
include/linux/huge_mm.h
View File

@ -237,6 +237,31 @@ static inline bool thp_vma_suitable_order(struct vm_area_struct *vma,
return true;
}
/*
* Make sure huge_gfp is always more limited than limit_gfp.
* Some shmem users want THP allocation to be done less aggressively
* and only in certain zone.
*/
static inline gfp_t thp_shmem_limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
{
gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
/* Allow allocations only from the originally specified zones. */
result |= zoneflags;
/*
* Minimize the result gfp by taking the union with the deny flags,
* and the intersection of the allow flags.
*/
result |= (limit_gfp & denyflags);
result |= (huge_gfp & limit_gfp) & allowflags;
return result;
}
/*
* Filter the bitfield of input orders to the ones suitable for use in the vma.
* See thp_vma_suitable_order().
@ -581,6 +606,11 @@ static inline bool thp_vma_suitable_order(struct vm_area_struct *vma,
return false;
}
static inline gfp_t thp_shmem_limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
{
return huge_gfp;
}
static inline unsigned long thp_vma_suitable_orders(struct vm_area_struct *vma,
unsigned long addr, unsigned long orders)
{

30
mm/shmem.c
View File

@ -1791,30 +1791,6 @@ static struct folio *shmem_swapin_cluster(swp_entry_t swap, gfp_t gfp,
return folio;
}
/*
* Make sure huge_gfp is always more limited than limit_gfp.
* Some of the flags set permissions, while others set limitations.
*/
static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
{
gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
/* Allow allocations only from the originally specified zones. */
result |= zoneflags;
/*
* Minimize the result gfp by taking the union with the deny flags,
* and the intersection of the allow flags.
*/
result |= (limit_gfp & denyflags);
result |= (huge_gfp & limit_gfp) & allowflags;
return result;
}
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
bool shmem_hpage_pmd_enabled(void)
{
@ -2065,7 +2041,7 @@ static struct folio *shmem_swap_alloc_folio(struct inode *inode,
non_swapcache_batch(entry, nr_pages) != nr_pages)
goto fallback;
alloc_gfp = limit_gfp_mask(vma_thp_gfp_mask(vma), gfp);
alloc_gfp = thp_shmem_limit_gfp_mask(vma_thp_gfp_mask(vma), gfp);
}
retry:
new = shmem_alloc_folio(alloc_gfp, order, info, index);
@ -2141,7 +2117,7 @@ static int shmem_replace_folio(struct folio **foliop, gfp_t gfp,
if (nr_pages > 1) {
gfp_t huge_gfp = vma_thp_gfp_mask(vma);
gfp = limit_gfp_mask(huge_gfp, gfp);
gfp = thp_shmem_limit_gfp_mask(huge_gfp, gfp);
}
#endif
@ -2548,7 +2524,7 @@ static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
gfp_t huge_gfp;
huge_gfp = vma_thp_gfp_mask(vma);
huge_gfp = limit_gfp_mask(huge_gfp, gfp);
huge_gfp = thp_shmem_limit_gfp_mask(huge_gfp, gfp);
folio = shmem_alloc_and_add_folio(vmf, huge_gfp,
inode, index, fault_mm, orders);
if (!IS_ERR(folio)) {