mm/huge_memory: convert "tva_flags" to "enum tva_type"

When determining which THP orders are eligible for a VMA mapping, we have
previously specified tva_flags, however it turns out it is really not
necessary to treat these as flags.

Rather, we distinguish between distinct modes.

The only case where we previously combined flags was with
TVA_ENFORCE_SYSFS, but we can avoid this by observing that this is the
default, except for MADV_COLLAPSE or an edge cases in
collapse_pte_mapped_thp() and hugepage_vma_revalidate(), and adding a mode
specifically for this case - TVA_FORCED_COLLAPSE.

We have:
* smaps handling for showing "THPeligible"
* Pagefault handling
* khugepaged handling
* Forced collapse handling: primarily MADV_COLLAPSE, but also for
  an edge case in collapse_pte_mapped_thp()

Disregarding the edge cases, we only want to ignore sysfs settings only
when we are forcing a collapse through MADV_COLLAPSE, otherwise we want to
enforce it, hence this patch does the following flag to enum conversions:

* TVA_SMAPS | TVA_ENFORCE_SYSFS -> TVA_SMAPS
* TVA_IN_PF | TVA_ENFORCE_SYSFS -> TVA_PAGEFAULT
* TVA_ENFORCE_SYSFS             -> TVA_KHUGEPAGED
* 0                             -> TVA_FORCED_COLLAPSE

With this change, we immediately know if we are in the forced collapse
case, which will be valuable next.

Link: https://lkml.kernel.org/r/20250815135549.130506-3-usamaarif642@gmail.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Usama Arif <usamaarif642@gmail.com>
Acked-by: Usama Arif <usamaarif642@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yafang <laoar.shao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index e8e7bef345313579efd84d5681dad8ada4040d1a..ced01cf3c5ab3f520fb1e42a8058c263674e03dd 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1369,8 +1369,8 @@ static int show_smap(struct seq_file *m, void *v)
        __show_smap(m, &mss, false);
 
        seq_printf(m, "THPeligible:    %8u\n",
-                  !!thp_vma_allowable_orders(vma, vma->vm_flags,
-                          TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL));
+                  !!thp_vma_allowable_orders(vma, vma->vm_flags, TVA_SMAPS,
+                                             THP_ORDERS_ALL));
 
        if (arch_pkeys_enabled())
                seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 22b8b067b295eafe9332b0500c6ef02a078a7441..92ea0b9771fae6abdb612aa78dda047f78472d9f 100644 (file)
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -94,12 +94,15 @@ extern struct kobj_attribute thpsize_shmem_enabled_attr;
 #define THP_ORDERS_ALL \
        (THP_ORDERS_ALL_ANON | THP_ORDERS_ALL_SPECIAL | THP_ORDERS_ALL_FILE_DEFAULT)
 
-#define TVA_SMAPS              (1 << 0)        /* Will be used for procfs */
-#define TVA_IN_PF              (1 << 1)        /* Page fault handler */
-#define TVA_ENFORCE_SYSFS      (1 << 2)        /* Obey sysfs configuration */
+enum tva_type {
+       TVA_SMAPS,              /* Exposing "THPeligible:" in smaps. */
+       TVA_PAGEFAULT,          /* Serving a page fault. */
+       TVA_KHUGEPAGED,         /* Khugepaged collapse. */
+       TVA_FORCED_COLLAPSE,    /* Forced collapse (e.g. MADV_COLLAPSE). */
+};
 
-#define thp_vma_allowable_order(vma, vm_flags, tva_flags, order) \
-       (!!thp_vma_allowable_orders(vma, vm_flags, tva_flags, BIT(order)))
+#define thp_vma_allowable_order(vma, vm_flags, type, order) \
+       (!!thp_vma_allowable_orders(vma, vm_flags, type, BIT(order)))
 
 #define split_folio(f) split_folio_to_list(f, NULL)
 
@@ -264,14 +267,14 @@ static inline unsigned long thp_vma_suitable_orders(struct vm_area_struct *vma,
 
 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
                                         vm_flags_t vm_flags,
-                                        unsigned long tva_flags,
+                                        enum tva_type type,
                                         unsigned long orders);
 
 /**
  * thp_vma_allowable_orders - determine hugepage orders that are allowed for vma
  * @vma:  the vm area to check
  * @vm_flags: use these vm_flags instead of vma->vm_flags
- * @tva_flags: Which TVA flags to honour
+ * @type: TVA type
  * @orders: bitfield of all orders to consider
  *
  * Calculates the intersection of the requested hugepage orders and the allowed
@@ -285,11 +288,14 @@ unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
 static inline
 unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
                                       vm_flags_t vm_flags,
-                                      unsigned long tva_flags,
+                                      enum tva_type type,
                                       unsigned long orders)
 {
-       /* Optimization to check if required orders are enabled early. */
-       if ((tva_flags & TVA_ENFORCE_SYSFS) && vma_is_anonymous(vma)) {
+       /*
+        * Optimization to check if required orders are enabled early. Only
+        * forced collapse ignores sysfs configs.
+        */
+       if (type != TVA_FORCED_COLLAPSE && vma_is_anonymous(vma)) {
                unsigned long mask = READ_ONCE(huge_anon_orders_always);
 
                if (vm_flags & VM_HUGEPAGE)
@@ -303,7 +309,7 @@ unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
                        return 0;
        }
 
-       return __thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders);
+       return __thp_vma_allowable_orders(vma, vm_flags, type, orders);
 }
 
 struct thpsize {
@@ -547,7 +553,7 @@ static inline unsigned long thp_vma_suitable_orders(struct vm_area_struct *vma,
 
 static inline unsigned long thp_vma_allowable_orders(struct vm_area_struct *vma,
                                        vm_flags_t vm_flags,
-                                       unsigned long tva_flags,
+                                       enum tva_type type,
                                        unsigned long orders)
 {
        return 0;

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index a2f476e7419a39fdd34144778178f9c20e105654..899d9ac86ecd4c80164a2f220345da16279965c7 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -99,12 +99,12 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma)
 
 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
                                         vm_flags_t vm_flags,
-                                        unsigned long tva_flags,
+                                        enum tva_type type,
                                         unsigned long orders)
 {
-       bool smaps = tva_flags & TVA_SMAPS;
-       bool in_pf = tva_flags & TVA_IN_PF;
-       bool enforce_sysfs = tva_flags & TVA_ENFORCE_SYSFS;
+       const bool smaps = type == TVA_SMAPS;
+       const bool in_pf = type == TVA_PAGEFAULT;
+       const bool enforce_sysfs = type != TVA_FORCED_COLLAPSE;
        unsigned long supported_orders;
 
        /* Check the intersection of requested and supported orders. */

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d8cfefe93031215c8fc398d38e4834c916f3c726..db6709294a85b1f1583793223f027b586efb9747 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -474,8 +474,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
 {
        if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) &&
            hugepage_pmd_enabled()) {
-               if (thp_vma_allowable_order(vma, vm_flags, TVA_ENFORCE_SYSFS,
-                                           PMD_ORDER))
+               if (thp_vma_allowable_order(vma, vm_flags, TVA_KHUGEPAGED, PMD_ORDER))
                        __khugepaged_enter(vma->vm_mm);
        }
 }
@@ -921,7 +920,8 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
                                   struct collapse_control *cc)
 {
        struct vm_area_struct *vma;
-       unsigned long tva_flags = cc->is_khugepaged ? TVA_ENFORCE_SYSFS : 0;
+       enum tva_type type = cc->is_khugepaged ? TVA_KHUGEPAGED :
+                                TVA_FORCED_COLLAPSE;
 
        if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
                return SCAN_ANY_PROCESS;
@@ -932,7 +932,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 
        if (!thp_vma_suitable_order(vma, address, PMD_ORDER))
                return SCAN_ADDRESS_RANGE;
-       if (!thp_vma_allowable_order(vma, vma->vm_flags, tva_flags, PMD_ORDER))
+       if (!thp_vma_allowable_order(vma, vma->vm_flags, type, PMD_ORDER))
                return SCAN_VMA_CHECK;
        /*
         * Anon VMA expected, the address may be unmapped then
@@ -1533,9 +1533,9 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
         * in the page cache with a single hugepage. If a mm were to fault-in
         * this memory (mapped by a suitably aligned VMA), we'd get the hugepage
         * and map it by a PMD, regardless of sysfs THP settings. As such, let's
-        * analogously elide sysfs THP settings here.
+        * analogously elide sysfs THP settings here and force collapse.
         */
-       if (!thp_vma_allowable_order(vma, vma->vm_flags, 0, PMD_ORDER))
+       if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_FORCED_COLLAPSE, PMD_ORDER))
                return SCAN_VMA_CHECK;
 
        /* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
@@ -2432,8 +2432,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
                        progress++;
                        break;
                }
-               if (!thp_vma_allowable_order(vma, vma->vm_flags,
-                                       TVA_ENFORCE_SYSFS, PMD_ORDER)) {
+               if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) {
 skip:
                        progress++;
                        continue;
@@ -2767,7 +2766,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start,
        BUG_ON(vma->vm_start > start);
        BUG_ON(vma->vm_end < end);
 
-       if (!thp_vma_allowable_order(vma, vma->vm_flags, 0, PMD_ORDER))
+       if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_FORCED_COLLAPSE, PMD_ORDER))
                return -EINVAL;
 
        cc = kmalloc(sizeof(*cc), GFP_KERNEL);

diff --git a/mm/memory.c b/mm/memory.c
index 002c28795d8b732fd6cefe79b66da3c00d124930..7b1e8f137fa3fb1c577baab697831fd4e3a94d92 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4515,8 +4515,8 @@ static struct folio *alloc_swap_folio(struct vm_fault *vmf)
         * Get a list of all the (large) orders below PMD_ORDER that are enabled
         * and suitable for swapping THP.
         */
-       orders = thp_vma_allowable_orders(vma, vma->vm_flags,
-                       TVA_IN_PF | TVA_ENFORCE_SYSFS, BIT(PMD_ORDER) - 1);
+       orders = thp_vma_allowable_orders(vma, vma->vm_flags, TVA_PAGEFAULT,
+                                         BIT(PMD_ORDER) - 1);
        orders = thp_vma_suitable_orders(vma, vmf->address, orders);
        orders = thp_swap_suitable_orders(swp_offset(entry),
                                          vmf->address, orders);
@@ -5063,8 +5063,8 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
         * for this vma. Then filter out the orders that can't be allocated over
         * the faulting address and still be fully contained in the vma.
         */
-       orders = thp_vma_allowable_orders(vma, vma->vm_flags,
-                       TVA_IN_PF | TVA_ENFORCE_SYSFS, BIT(PMD_ORDER) - 1);
+       orders = thp_vma_allowable_orders(vma, vma->vm_flags, TVA_PAGEFAULT,
+                                         BIT(PMD_ORDER) - 1);
        orders = thp_vma_suitable_orders(vma, vmf->address, orders);
 
        if (!orders)
@@ -6254,8 +6254,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
                return VM_FAULT_OOM;
 retry_pud:
        if (pud_none(*vmf.pud) &&
-           thp_vma_allowable_order(vma, vm_flags,
-                               TVA_IN_PF | TVA_ENFORCE_SYSFS, PUD_ORDER)) {
+           thp_vma_allowable_order(vma, vm_flags, TVA_PAGEFAULT, PUD_ORDER)) {
                ret = create_huge_pud(&vmf);
                if (!(ret & VM_FAULT_FALLBACK))
                        return ret;
@@ -6289,8 +6288,7 @@ retry_pud:
                goto retry_pud;
 
        if (pmd_none(*vmf.pmd) &&
-           thp_vma_allowable_order(vma, vm_flags,
-                               TVA_IN_PF | TVA_ENFORCE_SYSFS, PMD_ORDER)) {
+           thp_vma_allowable_order(vma, vm_flags, TVA_PAGEFAULT, PMD_ORDER)) {
                ret = create_huge_pmd(&vmf);
                if (!(ret & VM_FAULT_FALLBACK))
                        return ret;