Re: [PATCH 0/8] __vmalloc() and no-block support

[Uladzislau Rezki <urezki@gmail.com>]

Hello, Alexander!

I am working on making vmalloc to support extra non-blocking flags.
Currently i see one more place that i need to address:

kmsan_vmap_pages_range_noflush() function which uses hard-coded GFP_KERNEL
flags for allocation of two arrays for its internal use only.

I have a question to you, can we just get rid of those two allocations?
It is the easiest way, if possible. Otherwise i can add "gfp_t gfp_mask"
extra parameter and pass there a corresponding gfp_mask flag. See below:

<snip>
diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h
index 2b1432cc16d5..e4b34e7a3b11 100644
--- a/include/linux/kmsan.h
+++ b/include/linux/kmsan.h
@@ -133,6 +133,7 @@ void kmsan_kfree_large(const void *ptr);
  * @prot:      page protection flags used for vmap.
  * @pages:     array of pages.
  * @page_shift:        page_shift passed to vmap_range_noflush().
+ * @gfp_mask:  gfp_mask to use internally.
  *
  * KMSAN maps shadow and origin pages of @pages into contiguous ranges in
  * vmalloc metadata address range. Returns 0 on success, callers must check
@@ -142,7 +143,8 @@ int __must_check kmsan_vmap_pages_range_noflush(unsigned long start,
                                                unsigned long end,
                                                pgprot_t prot,
                                                struct page **pages,
-                                               unsigned int page_shift);
+                                               unsigned int page_shift,
+                                               gfp_t gfp_mask);

 /**
  * kmsan_vunmap_kernel_range_noflush() - Notify KMSAN about a vunmap.
@@ -348,7 +350,7 @@ static inline void kmsan_kfree_large(const void *ptr)

 static inline int __must_check kmsan_vmap_pages_range_noflush(
        unsigned long start, unsigned long end, pgprot_t prot,
-       struct page **pages, unsigned int page_shift)
+       struct page **pages, unsigned int page_shift, gfp_t gfp_mask)
 {
        return 0;
 }
diff --git a/mm/internal.h b/mm/internal.h
index 45b725c3dc03..6a13b8ee1e6c 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1359,7 +1359,7 @@ size_t splice_folio_into_pipe(struct pipe_inode_info *pipe,
 #ifdef CONFIG_MMU
 void __init vmalloc_init(void);
 int __must_check vmap_pages_range_noflush(unsigned long addr, unsigned long end,
-                pgprot_t prot, struct page **pages, unsigned int page_shift);
+               pgprot_t prot, struct page **pages, unsigned int page_shift, gfp_t gfp_mask);
 unsigned int get_vm_area_page_order(struct vm_struct *vm);
 #else
 static inline void vmalloc_init(void)
@@ -1368,7 +1368,7 @@ static inline void vmalloc_init(void)

 static inline
 int __must_check vmap_pages_range_noflush(unsigned long addr, unsigned long end,
-                pgprot_t prot, struct page **pages, unsigned int page_shift)
+               pgprot_t prot, struct page **pages, unsigned int page_shift, gfp_t gfp_mask)
 {
        return -EINVAL;
 }
diff --git a/mm/kmsan/init.c b/mm/kmsan/init.c
index b14ce3417e65..5b74d6dbf0b8 100644
--- a/mm/kmsan/init.c
+++ b/mm/kmsan/init.c
@@ -233,5 +233,6 @@ void __init kmsan_init_runtime(void)
        kmsan_memblock_discard();
        pr_info("Starting KernelMemorySanitizer\n");
        pr_info("ATTENTION: KMSAN is a debugging tool! Do not use it on production machines!\n");
-       kmsan_enabled = true;
+       /* kmsan_enabled = true; */
+       kmsan_enabled = false;
 }
diff --git a/mm/kmsan/shadow.c b/mm/kmsan/shadow.c
index 54f3c3c962f0..3cd733663100 100644
--- a/mm/kmsan/shadow.c
+++ b/mm/kmsan/shadow.c
@@ -215,7 +215,7 @@ void kmsan_free_page(struct page *page, unsigned int order)

 int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
                                   pgprot_t prot, struct page **pages,
-                                  unsigned int page_shift)
+                                  unsigned int page_shift, gfp_t gfp_mask)
 {
        unsigned long shadow_start, origin_start, shadow_end, origin_end;
        struct page **s_pages, **o_pages;
@@ -230,8 +230,8 @@ int kmsan_vmap_pages_range_noflush(unsigned long start, unsigned long end,
                return 0;

        nr = (end - start) / PAGE_SIZE;
-       s_pages = kcalloc(nr, sizeof(*s_pages), GFP_KERNEL);
-       o_pages = kcalloc(nr, sizeof(*o_pages), GFP_KERNEL);
+       s_pages = kcalloc(nr, sizeof(*s_pages), gfp_mask);
+       o_pages = kcalloc(nr, sizeof(*o_pages), gfp_mask);
        if (!s_pages || !o_pages) {
                err = -ENOMEM;
                goto ret;
diff --git a/mm/percpu-vm.c b/mm/percpu-vm.c
index cd69caf6aa8d..4f5937090590 100644
--- a/mm/percpu-vm.c
+++ b/mm/percpu-vm.c
@@ -194,7 +194,7 @@ static int __pcpu_map_pages(unsigned long addr, struct page **pages,
                            int nr_pages)
 {
        return vmap_pages_range_noflush(addr, addr + (nr_pages << PAGE_SHIFT),
-                                       PAGE_KERNEL, pages, PAGE_SHIFT);
+                       PAGE_KERNEL, pages, PAGE_SHIFT, GFP_KERNEL);
 }

 /**
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ee197f5b8cf0..9be01dcca690 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -671,16 +671,28 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
 }

 int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
-               pgprot_t prot, struct page **pages, unsigned int page_shift)
+               pgprot_t prot, struct page **pages, unsigned int page_shift,
+               gfp_t gfp_mask)
 {
        int ret = kmsan_vmap_pages_range_noflush(addr, end, prot, pages,
-                                                page_shift);
+                                               page_shift, gfp_mask);

        if (ret)
                return ret;
        return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
 }

+static int __vmap_pages_range(unsigned long addr, unsigned long end,
+               pgprot_t prot, struct page **pages, unsigned int page_shift,
+               gfp_t gfp_mask)
+{
+       int err;
+
+       err = vmap_pages_range_noflush(addr, end, prot, pages, page_shift, gfp_mask);
+       flush_cache_vmap(addr, end);
+       return err;
+}
+
 /**
  * vmap_pages_range - map pages to a kernel virtual address
  * @addr: start of the VM area to map
@@ -696,11 +708,7 @@ int vmap_pages_range_noflush(unsigned long addr, unsigned long end,
 int vmap_pages_range(unsigned long addr, unsigned long end,
                pgprot_t prot, struct page **pages, unsigned int page_shift)
 {
-       int err;
-
-       err = vmap_pages_range_noflush(addr, end, prot, pages, page_shift);
-       flush_cache_vmap(addr, end);
-       return err;
+       return __vmap_pages_range(addr, end, prot, pages, page_shift, GFP_KERNEL);
 }

 static int check_sparse_vm_area(struct vm_struct *area, unsigned long start,
@@ -3804,8 +3812,8 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
                flags = memalloc_noio_save();

        do {
-               ret = vmap_pages_range(addr, addr + size, prot, area->pages,
-                       page_shift);
+               ret = __vmap_pages_range(addr, addr + size, prot, area->pages,
+                               page_shift, gfp_mask);
                if (nofail && (ret < 0))
                        schedule_timeout_uninterruptible(1);
        } while (nofail && (ret < 0));
<snip>

Thanks!

--
Uladzislau Rezki