* Re: [PATCHv2 3/8] mm: Accept memory in __alloc_pages_bulk(). [not found] ` <20240809114854.3745464-4-kirill.shutemov@linux.intel.com> @ 2024-08-09 15:31 ` Tom Lendacky 2024-08-12 6:24 ` Kirill A. Shutemov 0 siblings, 1 reply; 3+ messages in thread From: Tom Lendacky @ 2024-08-09 15:31 UTC (permalink / raw) To: Kirill A. Shutemov, Andrew Morton, Borislav Petkov (AMD), Mel Gorman, Vlastimil Babka Cc: Mike Rapoport, Matthew Wilcox (Oracle), David Hildenbrand, Johannes Weiner, linux-mm, linux-kernel On 8/9/24 06:48, Kirill A. Shutemov wrote: > Currently, the kernel only accepts memory in get_page_from_freelist(), > but there is another path that directly takes pages from free lists - > __alloc_page_bulk(). This function can consume all accepted memory and > will resort to __alloc_pages_noprof() if necessary. > > Conditionally accepted in __alloc_pages_bulk(). > > The same issue may arise due to deferred page initialization. Kick the > deferred initialization machinery before abandoning the zone, as the > kernel does in get_page_from_freelist(). Is the deferred page init issue an existing problem? In other words, should it be a separate patch with a Fixes: tag so it can go back to stable kernels? Thanks, Tom > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Acked-by: David Hildenbrand <david@redhat.com> > --- > mm/page_alloc.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index f7bb885aab07..ed62ecd6775f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4613,12 +4613,23 @@ unsigned long alloc_pages_bulk_noprof(gfp_t gfp, int preferred_nid, > goto failed; > } > > + cond_accept_memory(zone, 0); > +retry_this_zone: > mark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK) + nr_pages; > if (zone_watermark_fast(zone, 0, mark, > zonelist_zone_idx(ac.preferred_zoneref), > alloc_flags, gfp)) { > break; > } > + > + if (cond_accept_memory(zone, 0)) > + goto retry_this_zone; > + > + /* Try again if zone has deferred pages */ > + if (deferred_pages_enabled()) { > + if (_deferred_grow_zone(zone, 0)) > + goto retry_this_zone; > + } > } > > /* ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCHv2 3/8] mm: Accept memory in __alloc_pages_bulk(). 2024-08-09 15:31 ` [PATCHv2 3/8] mm: Accept memory in __alloc_pages_bulk() Tom Lendacky @ 2024-08-12 6:24 ` Kirill A. Shutemov 0 siblings, 0 replies; 3+ messages in thread From: Kirill A. Shutemov @ 2024-08-12 6:24 UTC (permalink / raw) To: Tom Lendacky Cc: Andrew Morton, Borislav Petkov (AMD), Mel Gorman, Vlastimil Babka, Mike Rapoport, Matthew Wilcox (Oracle), David Hildenbrand, Johannes Weiner, linux-mm, linux-kernel On Fri, Aug 09, 2024 at 10:31:03AM -0500, Tom Lendacky wrote: > On 8/9/24 06:48, Kirill A. Shutemov wrote: > > Currently, the kernel only accepts memory in get_page_from_freelist(), > > but there is another path that directly takes pages from free lists - > > __alloc_page_bulk(). This function can consume all accepted memory and > > will resort to __alloc_pages_noprof() if necessary. > > > > Conditionally accepted in __alloc_pages_bulk(). > > > > The same issue may arise due to deferred page initialization. Kick the > > deferred initialization machinery before abandoning the zone, as the > > kernel does in get_page_from_freelist(). > > Is the deferred page init issue an existing problem? In other words, > should it be a separate patch with a Fixes: tag so it can go back to > stable kernels? Yes, it is existing problem, but the problem is transient (deferred thread will add more pages) and there's fallback to __alloc_pages_noprof() which knowns how to handle deferred pages. I don't think it is worth backporting. -- Kiryl Shutsemau / Kirill A. Shutemov ^ permalink raw reply [flat|nested] 3+ messages in thread
[parent not found: <20240809114854.3745464-2-kirill.shutemov@linux.intel.com>]
* Re: [PATCHv2 1/8] mm: Fix endless reclaim on machines with unaccepted memory [not found] ` <20240809114854.3745464-2-kirill.shutemov@linux.intel.com> @ 2024-08-12 22:12 ` Jianxiong Gao 0 siblings, 0 replies; 3+ messages in thread From: Jianxiong Gao @ 2024-08-12 22:12 UTC (permalink / raw) To: Kirill A. Shutemov Cc: Andrew Morton, Borislav Petkov (AMD), Mel Gorman, Vlastimil Babka, Tom Lendacky, Mike Rapoport, Matthew Wilcox (Oracle), David Hildenbrand, Johannes Weiner, linux-mm, linux-kernel, stable On Fri, Aug 9, 2024 at 4:49 AM Kirill A. Shutemov <kirill.shutemov@linux.intel.com> wrote: > > Unaccepted memory is considered unusable free memory, which is not > counted as free on the zone watermark check. This causes > get_page_from_freelist() to accept more memory to hit the high > watermark, but it creates problems in the reclaim path. > > The reclaim path encounters a failed zone watermark check and attempts > to reclaim memory. This is usually successful, but if there is little or > no reclaimable memory, it can result in endless reclaim with little to > no progress. This can occur early in the boot process, just after start > of the init process when the only reclaimable memory is the page cache > of the init executable and its libraries. > > Make unaccepted memory free from watermark check point of view. This way > unaccepted memory will never be the trigger of memory reclaim. > Accept more memory in the get_page_from_freelist() if needed. > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Reported-by: Jianxiong Gao <jxgao@google.com> > Acked-by: David Hildenbrand <david@redhat.com> > Fixes: dcdfdd40fa82 ("mm: Add support for unaccepted memory") > Cc: stable@vger.kernel.org # v6.5+ Tested-by: Jianxiong Gao <jxgao@google.com> I have verified that the patch fixes the systemd issue reported. ^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-08-09 15:31 ` [PATCHv2 3/8] mm: Accept memory in __alloc_pages_bulk() Tom Lendacky
2024-08-12 6:24 ` Kirill A. Shutemov
[not found] ` <20240809114854.3745464-2-kirill.shutemov@linux.intel.com>
2024-08-12 22:12 ` [PATCHv2 1/8] mm: Fix endless reclaim on machines with unaccepted memory Jianxiong Gao
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