lib/test_free_pages.c: pass a pointer to virt_to_page()

In a recent change to the Arm architecture with the end goal of removing
highmem we need to convert virt_to_phys() and virt_to_pfn() to static
inline functions.

This will make them strongly typed.

However since virt_to_* is always implemented as macros they have become
polymorphic and accept both (void *) and e.g. unsigned long as arguments.

Other functions such as virt_to_page() simply wrap virt_to_pfn() and get
affected indirectly.

To be able to proceed, patch mm to use (void *) as argument to affected
functions in all instances.


This patch (of 5):

A pointer into virtual memory is represented by a (void *) not an u32, so
the compiler warns:

lib/test_free_pages.c:20:50: warning: passing argument 1
of 'virt_to_pfn' makes pointer from integer without a
cast [-Wint-conversion]

Fix this with an explicit cast.

Link: https://lkml.kernel.org/r/20220630084124.691207-1-linus.walleij@linaro.org
Link: https://lkml.kernel.org/r/20220630084124.691207-2-linus.walleij@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/test_free_pages.c: add basic progress indicators

The test module to check that free_pages() does not leak memory does not
provide any feedback whatsoever its state or progress, but may take some
time on slow machines. Add the printing of messages upon starting each
phase of the test, and upon completion.

Link: https://lkml.kernel.org/r/20201018140445.20972-1-geert@linux-m68k.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c: fix freeing non-compound pages

Here is a very rare race which leaks memory:

Page P0 is allocated to the page cache. Page P1 is free.

Thread A Thread B Thread C
find_get_entry():
xas_load() returns P0
Removes P0 from page cache
P0 finds its buddy P1
alloc_pages(GFP_KERNEL, 1) returns P0
P0 has refcount 1
page_cache_get_speculative(P0)
P0 has refcount 2
__free_pages(P0)
P0 has refcount 1
put_page(P0)
P1 is not freed

Fix this by freeing all the pages in __free_pages() that won't be freed
by the call to put_page(). It's usually not a good idea to split a page,
but this is a very unlikely scenario.

Fixes: e286781d5f2e ("mm: speculative page references")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200926213919.26642-1-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>