Close all file descriptors for a process before starting its core dump?

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Hi VFS and kernel experts,

I'd like to ask help about whether kernel can close all file
descriptors for a process
just before starting this process's core dump?

We have an application that uses large amount of memory (80G). When it panic
and core dump, it will need a long time to save the core file. During
which, file
locks held by this application will block other processes accessing
this file for a
long time, this causes bad end-user experience

I have a kernel customization which closes all file descriptors for
this process just
before starting its core dump. This way any file locks held by this
process can be
released automatically inside kernel before core dump.

I am wondering whether this kernel customization can cause any side effects for
the user land process memory state? I roughly went through mmap/socket/fifo/
pipe/sysv-ipc code, it looks closing files from inside kernel doesn't
change user
land process's memory content. However I am not sure, so I would like to ask
help and confirm from you.

Thanks a lot!
Jason
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